Fifty is also half of 100, which has a similar meaning; the Writings tell us that when used together with 100, fifty represents an intermediate state. God rested on the seventh day of creation. That represents a state of holiness and tranquility that was preserved in the form of the sabbath. Holier still was the seventh sabbath, which happened every 49 days. The Israelites would follow that solemn day with the “feast of the seven sabbaths” on the 50th day, and for similar reasons had a jubilee year every 50th year. For these reasons, among others, “fifty” in the Bible is the completion of a cycle, and in most cases represents fullness or sufficiency.

'The feast of the Passover' signifies celebration of the Lord because of liberation from damnation, which is effected by regeneration. In the highest sense, it was a memorial of the glorification of the Lord's humanity, because that liberation comes from this glorification. 'The Passover,' in Exodus 12:27, signifies the presence of the Lord and His liberation from damnation of the people of the spiritual church. 'The Passover' signifies the Lord's glorification, that is, the taking on of the divine regarding the human, and in a representative sense, it signifies the regeneration of mankind.

(Reference: Arcana Coelestia 7093, 7807, 7938)