1. They plead what he had done for his people Israel in particular when he brought them out of Egypt, v. 3. He then did terrible things in the plagues of Egypt, which they looked not for; they despaired of deliverance, so far were they from any thought of being delivered with such a high hand and outstretched arm. Then he came down upon Mount Sinai in such terror as made that and the adjacent mountains to flow down at his presence, to skip like rams (Ps. cxiv. 4), to tremble, so that they were scattered and the perpetual hills were made to bow, Hab. iii. 6. In the many great salvations God wrought for that people he did terrible things which they looked not for, made great men, that seemed as stately and strong as mountains, to fall before him, and great opposition to give way. See Judg. v. 4, 5; Ps. lxviii. 7, 8. Some refer this to the defeat of Sennacherib's powerful army, which was as surprising an instance of the divine power as the melting down of rocks and mountains would be.