Thenceforth were your hearts hardened: They became like a rock and even worse in hardness. For among rocks there are some from which rivers gush forth; others there are which when split asunder send forth water; and others which sink for fear of Allah. And Allah is not unmindful of what ye do.
The following excerpt is taken from Maariful Quran pg. 238-239 Vol 1:
The Surah has been relating a number of incidents which show
that the Israelites were always prone to disobedience and rebellion and had to undergo punishment again and again. Such an experience should have taught them humility and obedience. On the contrary, their hearts became all the more hardened against divine guidance.
This insensibility led them into further misdeeds and transgressions.
The present verse describes their degeneracy, and warns them that
Allah knows everything they have been doing, and will punish them
for their evil deeds.
Shafi, Muhammad (2008). Maariful Quran. (Vol .1 pg. 239) http://www.islamicweblibrary.com/wp-content/uploads/2020/04/maarif-volum1-english.pdf