Charles Ellicott Commentary Genesis 21:8

"And the child grew, and was weaned. And Abraham made a great feast on the day that Isaac was weaned." — Genesis 21:8 (ASV)

The child grew, and was weaned. — According to tradition, Isaac was two years old when weaned. Three years is the age mentioned in 2 Chronicles 31:16, 2 Maccabees 7:27; and Samuel was old enough at his weaning to be left at the tabernacle with Eli (1 Samuel 1:24). In Persia and India it is still the custom to celebrate the weaning of a child by an entertainment.