Numbers 9:5
And they kept the passover on the fourteenth day of the first month at even in the wilderness of Sinai: according to all that the LORD commanded Moses, so did the children of Israel. And they kept the passover on the fourteenth day of the first month at even in the wilderness of Sinai: according to all that the LORD commanded Moses, so did the children of Israel.
The keeping took place in the wilderness of Sinai, the first location of the sanctuary, while Israel remained during its nearly year-long stay at Horeb. They kept the Passover there on the fourteenth day of the first month at even, according to all that the Lord commanded Moses.
This was the observance in the year after the deliverance from Egypt, the first Passover celebrated after leaving Egypt. It was the only Passover observed during the wilderness sojourn, with regular observance to resume after entering Canaan.
All the feasts given to Israel occurred annually and were to be observed only when due, with the single exception that those unable to keep the Passover in the first month on account of ceremonial uncleanness were allowed to keep it on the same day of the month in the second month.
The account belongs to the ceremonies and the strict order established among the people, by which they learned discipline and systematic conduct. The Passover was roasted on the evening after the fourteenth day of the first month, so that its observance in the promised land would sometimes fall on the Sabbath and require cooking fires, showing that the prohibition of fires in Exodus 35:3 was a temporary rule for the wilderness and not a lasting Sabbath law for Canaan.