Deuteronomy 7:23

But the Lord your God will give them up before you, and will trouble them with great trouble, until they shall be consumed

והמם מהומה גדולה, the construction of והמם, i.e. the vowel pattern of two successive letters מ and the two vowels kametz in succession is clearly parallel to וסבב בית אל in Samuel I 7,16 with the two letters ב, or as in Lamentations 5,18 שמם from שממה. The meaning of the phrase is that G’d made these people hear such powerful and earsplitting noise during the battle that this contributed greatly to their destruction. If we were to assume that the second letter מ is a pronoun ending meaning אותם, “them,” the vowel pattern should have been vehamaman. Seeing that the root of the word is המה as in יהמה לבי (Jeremiah 48,36) “my heart moans, etc.”, the Torah wrote vehamam, i.e. “He made them moan.” We find a line with similar meaning in Isaiah 48,5 עצבי עשם, “my carved images were the cause of this,” the word עשם being derived from the root עשה, or Genesis 29,10 כאשר ראה יעקב something which is referred to later in Genesis 32,3 as כאשר ראם, “when he saw them.” The root המה determines the construction here.
If you were to say that the final letter ם was a sign of the pronoun “them,” as in the examples from Isaiah and Lamentations we have quoted, this is impossible, as the expression המיון, which implies something that is part of the human body, as in Isaiah 16,11 and Jeremiah 48,36, or in Psalms 46,4 יהמו יחמרו מימיו, “its waters rage and foam;” i.e. this is self-generated, not the result of action by outsiders. If the word were in the transitive mode, hiphil, the vowel pattern would have had to be vehimah, just as in the root כלה, for instance, the vowel pattern if it appeared in the transitive mode, hiphil, the vowel pattern would have to be kilah. Or it would have to be כלם, kilam as the case would be if the final letter ם were used as the pronoun ending for “them,” as in Lamentations 2,22 or 4,11. When used transitively, the root שנה meaning changing, exchanging, such as clothes, would be שנא, shina, in the plain past tense, as in Kings II 25,29, or וישניה, vayehshaneha, in the past tense introduced by the letter ו changing a future mode to a past mode, as in Esther 2,9.