Thomas Aquinas Commentary Lamentations 2:20

"See, O Jehovah, and behold to whom thou hast done thus! Shall the women eat their fruit, the children that are dandled in the hands? Shall the priest and the prophet be slain in the sanctuary of the Lord?" — Lamentations 2:20 (ASV)

Here the prophet presents his prayer.

First, he appeals for mercy because of the cruelty of the punishment.

Second, because of its universality, as it is written: the child and the old man lie outside on the ground (Lamentations 2:21).

Third, because of the impossibility of escape, as it says: you have called as to a festival (Lamentations 2:22).

Regarding the first point, he does two things.

1. He calls for God’s attention with the cry, “Whom have you harvested so cruelly?” This is as if to say, “No one other than me,” or, “Who is there like I am?” because I was chosen from among my fathers. The prophet says elsewhere, The LORD has made a vintage of me in the day of his fierce anger (Lamentations 1:12).
2. He presents the cruelty of the punishment, which violates natural affection, asking: shall women then eat their own fruit? This is as if to say, “Can you really allow this?” We read in Josephus and Hegesippus that this was done during the siege by the Romans, and in 2 Kings 5 and 7 at the siege of Samaria. This is confirmed in another passage: The hands of the pitiful women have boiled their own children (Lamentations 4:10).

The punishment also defies true religion, for he asks, shall the priest and the prophet be slain in the sanctuary of the Lord? This is as if to say, “Can you really allow them to be killed?” Yet God Himself had commanded, Begin at my sanctuary (Ezekiel 9:6).