וְ֭אֵל הֵרַ֣ךְ לִבִּ֑י וְ֝שַׁדַּ֗י הִבְהִילָֽנִי׃
上帝使我心裡發軟，全能者使我驚惶。
Rashbam
מרך בלבבם, this does not mean that the heart has become soft, as in Deuteronomy 20,8 or as in Job 23,16, but the letter מ in the word מרך is an integral part of the word, not a preposition. In fact, even the emphasis is on that letter, as in the word אהל, tent. The word and its intonation is similar to Isaiah 58,13 וקראת לשבת עונג, and the word אוכל, ochel, which is intoned on the first syllable. The word מרך does not appear again in Scriptures.