Sefer HaBahir 19

1[Rabbi Amorai continued,] “And why is [the letter] Gimmel third? Because it has three parts, and to inform us that she bestows [גומלת] acts of lovingkindness." [They asked him,] "And didn't Rabbi Akiva [already] say, ‘Why is Gimmel in three parts? Because she weans [גומלת], grows [מתגדלת], and sustains [מתקיימת],’ as it is said ‘And the boy grew up [ויגדל] and was weaned [ויגמל]' (Genesis 21:8)." He said to them, "It is my words [that Rabbi Akiva said], for he grew up [גודל] and bestowed [גומל] lovingkindness to his neighbors, his people, and those who trusted him."