Sforno on Numbers 9:2/ספורנו על במדבר ט׳:ב׳

1ויעשו בני ישראל את הפסח, apart from the procedures reported as having taken place on the eighth day of the consecration of the Tabernacle, and the consecration of the princes between the first and twelfth of the month of Nissan, 2 days later the whole nation observed the Passover. They did not feel that they had become free from doing so seeing that they had just finished a string of rituals as a result of which they were on a spiritual “high,” full of joy. This was in contrast to the consecration of Solomon’s Temple, on the occasion of which, according to our sages in Moed Katan 9, Solomon ordered a dispensation of the Day of Atonement seeing that the people were on such a spiritual “high” on account of that event.