Charles Ellicott Commentary Psalms 114:7

"Tremble, thou earth, at the presence of the Lord, At the presence of the God of Jacob," — Psalms 114:7 (ASV)

Tremble. —Literally, be in travail. This answer to his question is introduced with consummate art.

The mountains may well tremble, when it is the Lord of all the earth, the God of Jacob, who is present. Notice that until now the mention of the Divine power which accomplished the deliverance was kept in suspense.