1. When Israel went out of Egypt, the House of Jacob from a people of a foreign tongue,
2. Judah became His holy [nation], Israel, His domain.
3. The sea saw and fled, the Jordan turned backward.
4. The mountains skipped like rams, the hills like young sheep.
5. What is the matter with you, O sea, that you flee; Jordan, that you turn backward;

Tehillim Ohel Yoseph Yitzchok (Kehot Publication Society)

Tehillim is recited by Jewish people collectively and individually, as the desire occurs to offer praise and thanksgiving to G-d; or alternitavely, in times of crisis and need, as a form of supplication, and even as a venue to express regret for sin.

6. mountains, that you skip like rams; hills, like young sheep?
7. [We do so] before the Master, the Creator of the earth, before the God of Jacob,
8. Who turns the rock into a pool of water, the flintstone into a water fountain.