Genesis 21:8

And the child grew, and was weaned: and Abraham made a great feast the same day that Isaac was weaned.

The child grew, ... Children are suckled longer in the East than in Europe-boys usually for two or three years; in some cases even for four or five (1 Samuel 1:22-28; 2 Chronicles 31:16: cf. 2Ma 8:27), 'My sons, have pity upon me that bare thee, and gave thee suck three years.'

Abraham made a great feast, ... In Eastern countries this is always a season of domestic festivity, and the newly-weaned child is formally brought, in presence of the assembled relatives and friends, to partake of some simple viands. Isaac, attired in the symbolic robe-the badge of birthright-was then admitted heir of the tribe (Rosenmuller).