וְהַנַּ֣עַר שְׁמוּאֵ֔ל הֹלֵ֥ךְ וְגָדֵ֖ל וָט֑וֹב גַּ֚ם עִם־יְהוָ֔ה וְגַ֖ם עִם־אֲנָשִֽׁים׃ (ס)
And the child Samuel grew on, and increased in favour both with the LORD, and also with men.
Rashi
was becoming greater - Heb. וְגָדֵל. Scripture uses] a similar expression in reference to three people: Isaac, Samuel, and Jehoshaphat, but concerning Moses, David, and Mordecai, it says וְגָדוֹל. Concerning Isaac, Samuel, and Jehoshaphat, it says, וְגָדֵל because it is not proper to say וְגָדוֹל, great [in the context in which the word appears in the verse]. In regards to Samuel, it says, (I Sam. 2: 21): “And the lad Samuel grew up with the Lord.” God forbid that it should say, גָדוֹל עִם ה', he was great with the Lord. Here too, he [Jehoshaphat] became great to an unusual degree, גָדֵל עַד לְמָעְלָה. It is therefore improper to say וְגָדוֹל, great. The same applies to Isaac.