Exodus 1:20

וַיֵּיטָב means HE DID GOOD TO THEM. — The following is the difference between certain forms in a word (verb) whose root is two letters when one prefixes ו and י to them: when it intends to express the meaning “and he caused someone or something to do a particular action” (i. e. the 3rd masc. sing, imperf. Hiphil with Vau conversive), the י has the vowel Tzéré which is what we call Kametz Katan, as, (in this verse) “And God dealt well (וַיֶּיטָב) with the midwives” (to Rashi the root it טב; we take it as יטב); (Lamentations 2:5) “וַיָרָב for the daughter of Judah [mourning]” i. e. He increased (made great) the mourning; (root רֹב; we take it as רבה). Similarly (II Chronicles 36:20) “וַיָּגָל the remnant” which occurs in connection with Nebuzaradon, i. e. he caused the remnant to be exiled; (Judges 15:4) וַיָּפָן tail to tail”, i. e. he turned the tails one towards the other (more lit., he caused one tail to turn to the other) — all these express the meaning “he caused others to do something” (i. e. they are of the Hiphil conjugation). When, however, it speaks in the sense of “and he did something” (3rd masc. sing, imperf. Kal with Vau conv.), the י has the vowel Chirik. For example, (Leviticus 10:20) “וַיִיטַב in his eyes” — this means, “it was good”. Similarly (in this verse) the people”, i. e. the people became many; (2 Kings 25:21) “וַיִגָל Judah”, i. e. Judah became an exile; (2:12) “וַיִפֵן this way and that way”, i. e. he turned this way and that way. Do not answer me (do not raise an objection) by quoting the words וַיֵּלֶךְ and וַיֵּשֶׁב and וַיַרֶד and וַיֵּצֵא (saying that these verbal forms also have ו and י prefixed and the י has the vowel Tzéré and yet they are Kal, not Hiphil forms), because these are not of the same class of verbs as those above-mentioned, for the י is part of the root in them — in יֵלֵךְ and יֵשֵׁב and יֵרֵד and יֵצֵא, the י is a third root letter in each of these. וייטב אלהים למילדת THEREFORE GOD DEALT WELL WITH THE MIDWIVES — What was the good He dealt out to them? The next verse gives the reply to this —

וַיֵּ֥יטֶב אֱלֹהִ֖ים לַֽמְיַלְּדֹ֑ת וַיִּ֧רֶב הָעָ֛ם וַיַּֽעַצְמ֖וּ מְאֹֽד׃

Therefore God dealt well with the midwives: and the people multiplied, and grew very mighty.