וַיִּגְדַּ֥ל הַיֶּ֖לֶד וַיִּגָּמַ֑ל וַיַּ֤עַשׂ אַבְרָהָם֙ מִשְׁתֶּ֣ה גָד֔וֹל בְּי֖וֹם הִגָּמֵ֥ל אֶת־יִצְחָֽק׃
And the child grew, and was weaned. And Abraham made a great feast on the day that Isaac was weaned.
Rashi on Genesis
ויגמל AND HE WAS WEANED — at the expiration of twenty- four months (Gittin 75b).
Rashbam on Genesis
ויגמל, he was separated from depending on his mother’s nipples.
Radak on Genesis
ויגדל הילד ויגמל , he stopped receiving mother’s milk. This occurred after he was 24 months old. This was the standard period that babies nursed at the breasts of their mothers.