Commento su Esodo 15:5

יכסימו THEY COVER THEM — this is the same as יְכַסּוּם and the middle י is redundant. This is quite usual in Scripture–verses (in Biblical Hebrew), just as in (Deuteronomy 8:13) וצאנך ירביון, and (Psalms 36:9) ירויון מדשן ביתך, and the force of the first י which expresses the future tense you must explain as follows: they have been sunk in the Red Sea in order that the waters should return and should cover them. The word יכסימו has no similar example in Scripture so far as its punctuation is concerned; ordinarily it would be יְכַסְיֻמוּ with Melopum (חולם)‎.

תהומות יכסיומו, the deeps covered them, etc. The reason the Torah speaks of תהום in the plural must be viewed in light of my comment on 14,21 that half the sea was frozen whereas the other half was split. Each part was originally part of what is called תהום. Read what I have written on 15,8: "the deeps were congealed, etc."

יכסיומו, we would have expected the vowel cholem on the letter ו at the end of this word, i.e. “covered it” (the Egyptian army). However on account of the vowel kubutz under the letter י in the same word the vowel shuruk was chosen for poetical considerations. We find a similar anomaly in Ezekiel 43,11 מוצאיו ומובואיו, where there appears to be no justification at all for the letter ו after the letter מ in the word ומובאיו. The letter was added to maintain a certain poetical meter. [I am far too ignorant of Hebrew poetry either classical or modern, to offer any opinion on this. I do know, however, that the root בא from a grammatical aspect does not require the additional letter ו. Ed.]