During the reigns of Hezekiah and Josiah, righteous kings of Judah, the observance of Passover underwent significant changes from God's original commands as given in Exodus 12, Numbers 9, and Leviticus 23. These changes were enforced by the kings themselves, who personally supervised the rituals to prevent a return to pagan practices, driven by the extreme idolatry and religious perversion that had deeply ingrained itself in the people. The Passovers under these kings included additional sacrifices from flocks and herds, such as burnt, peace, and thank offerings, which were typically offered during the Days of Unleavened Bread, marking a departure from the singular focus on the Passover lamb. Despite these deviations, God accepted these Temple-centered Passovers due to the hardness of heart among the people, deeming them better than no observance at all under such dire spiritual circumstances. However, this acceptance did not alter His original intent for a domestic-killed Passover celebrated at home, as evidenced by historical accounts from Josephus and Philo, which note that many Jews, even at the time of Christ, continued to sacrifice the Passover lamb at home rather than at the Temple. This resulted in two distinct Passover practices: a larger group adhering to the home sacrifice and a smaller group of religious leaders following the Temple-centered tradition established under Hezekiah and Josiah. The responsibility remains to observe Passover according to God's initial command and the example of Jesus Christ, who kept it at the beginning of the 14th day, using the new symbols He instituted, rather than following later traditions, regardless of their apparent good intent or the positive outcomes during the times of Hezekiah and Josiah. Additionally, an examination of Deuteronomy 16 suggests it has been altered over time, with the term Passover inserted to support a Temple-centered, 15th-day observance, contradicting the clear domestic instructions in earlier scriptures. This tampering likely occurred after the Babylonian captivity when the entire spring festival was commonly referred to as Passover, yet God's original command never endorsed a 15th-day Passover, maintaining the 14th-day domestic sacrifice as the true standard.

The instructions in Deuteronomy 16, as originally given by God, were for Unleavened Bread and not Passover. The word Passover was inserted into the text at a later time, likely after the Jews returned from Babylonian captivity, when both feasts were commonly referred to as Passover. This editing created the appearance of a 15th Passover, though God never commanded such a date. Deuteronomy 16 was chosen for alteration because it lacks specific numbered dates, making the change less obvious compared to texts like Exodus 12, Numbers 9, and Leviticus 23, where altering numbers would be evident tampering. The change involved replacing Unleavened Bread with Passover and asserting that the going down of the sun and between the two evenings are the same, a claim still made by some today, despite evidence in Exodus 16:12-13 showing that between the two evenings follows the going down of the sun. Historically, this alteration may have occurred during or after the time of Ezra, around 530 BC to 515 BC, when the Jews, post-captivity, were veering from God's law. Ezra, aware of the precedents set by Hezekiah and Josiah who controlled Passover and Unleavened Bread observances through royal command, centralized worship in the priesthood, Temple, and Sanhedrin to prevent further sin and captivity. Despite good intentions, neither Ezra, Hezekiah, nor Josiah had the authority to make permanent changes to what God originally commanded. Jesus Christ provides clarity on this matter through His actions. He did not observe Passover according to the altered traditions of men, such as a 15th Passover, but adhered to the original commandments given in Exodus 12, Leviticus 23, and Numbers 9. His observance at the beginning of the 14th, as seen in John 13:1, aligns with the timing specified in these scriptures, distinguishing His Passover from the later observance of the Jews. Jesus consistently denounced the traditions of men that transgressed God's commandments, as evidenced in His life and teachings, reinforcing that He would not have followed a man-made 15th Passover.

Passover, as originally instituted by God, occurred at the beginning of the fourteenth day, with the lamb killed at home, its blood sprinkled on the doorposts, and eaten on the night of the fourteenth to commemorate the event. The entire day was devoted to preparations, including slaying, cleaning, and roasting the lamb, staying in houses through the Death Angel's passing, burning the remains, and gathering for departure during daylight. God demanded work on that day, marking it as a festival but not a holy day, setting a pattern for all Passovers to follow. However, man altered this observance over time. The traditional practice shifted to killing the lamb at the end of the fourteenth day at the temple, with blood sprinkled on the altar and fat burned there. The lamb was eaten on the night of the fifteenth, commemorating the Exodus rather than Passover itself. Additionally, the seven days of Unleavened Bread were incorrectly termed Passover, reducing the total observance to seven days instead of eight. These changes significantly altered the meaning of Passover and Unleavened Bread, deviating from God's original command. Despite detailed instructions for sacrifices at the tabernacle and temple for every day, Sabbath, new moon, and feast day, no command exists in the first five books of Scripture to sacrifice a Passover lamb at the tabernacle or temple. God intended Passover to remain a domestically killed sacrifice and observed festival at home, with no holy convocation suggested. Even after the establishment of the priesthood and tabernacle, God made no change to the original observance, maintaining it as it was first given. Yet, scholars and proponents of a later Passover timing cling to singular verses suggesting a different practice, ignoring overwhelming evidence supporting the early fourteenth observance.

The observance of Passover, as originally commanded by God in Exodus 12, was to have the lamb slain at the beginning of the 14th day, with preparations made during the daytime of the 14th for departure, and the exodus from Egypt occurring by night at the start of the 15th. However, over time, this practice was altered by human intervention, resulting in a late 14th-15th Passover observance. This shift is evident in the actions of Judah, who, despite witnessing the captivity of Israel due to disobedience, failed to heed the warning and instead adopted similar pagan practices, becoming even more culpable before God. During the reign of Hezekiah, a significant deviation occurred when he assumed control over religious reforms due to a spiritual emergency. Hezekiah commanded the observance of Passover and the Days of Unleavened Bread in the second month, bending the rules to address the dire state of the nation, though this was not according to a direct command from God. He moved the Passover sacrifice to the Temple for supervision, marking the first scriptural indication of linking Passover with the Days of Unleavened Bread, a practice later reflected in the common terminology of the Jews during Jesus' time. Similarly, under Josiah, another national emergency prompted the king to enforce a Passover observance with strict oversight, ensuring it was not corrupted by pagan influences. Josiah's Passover also showed a blending of traditions, with the entire eight-day period being referred to as Passover, a notable change from earlier distinctions. Additional offerings beyond the Passover lamb were included, and sacrifices potentially extended into the 15th day due to the volume at the Temple, further diverging from the original command. These changes, driven by kings in times of crisis, highlight a pattern of human alteration to God's original instructions. Though possibly accepted by God under the circumstances, such deviations were not His ideal, and there is no explicit divine command to support these shifts. The influence of these reforms contributed to later traditions, such as the Temple-centric Passover and the merging of Passover with Unleavened Bread, which appear to contradict earlier, clearer commands given by God.