EBC Abridged: “The Hallel psalms are found in three separate collections: the “Egyptian Hallel” (113-118), the “Great Hallel” (120-136), and the concluding Hallel psalms (146-150)….The Egyptian Hallel and the Great Hallel were sung during the annual feasts (Lev 23; Nu 10:10). The Egyptian Hallel psalms received a special place in the Passover liturgy, as 113-114 were recited or sung before and 115-118 after the festive meal (cf. Mt 26:30; Mk 14:26). The concluding Hallel psalms (146-150) were incorporated in the daily prayers in the synagogue after the destruction of the temple (A.D. 70).”

Psalms 114:1 ¶ When Israel went out of Egypt, the house of Jacob from a people of strange language;

Psalms 114:2 Judah was his sanctuary, and Israel his dominion.

The psalmist opens by remembering how God delivered “the house of Jacob,” the people of Israel, from Egypt, a place where the people spoke a language foreign to them.   He jumps over the years of wandering in the wilderness to recall how God had established His people in the Promised Land.  He established the tribal land of Judah as His sanctuary, His earthly dwelling place represented by the temple, and the land of Israel as a whole as His kingdom.  Though He allowed them to form a government headed by an earthly king, the LORD was always to be acknowledged as the supreme authority.

Reminder: God had chosen Israel as His peculiar possession among all the nations.

Deuteronomy 7:6–8 “For thou art an holy people unto the LORD thy God: the LORD thy God hath chosen thee to be a special people unto himself, above all people that are upon the face of the earth. The LORD did not set his love upon you, nor choose you, because ye were more in number than any people; for ye were the fewest of all people: But because the LORD loved you, and because he would keep the oath which he had sworn unto your fathers, hath the LORD brought you out with a mighty hand, and redeemed you out of the house of bondmen, from the hand of Pharaoh king of Egypt.”

Psalms 114:3 The sea saw it, and fled: Jordan was driven back.

Psalms 114:4 The mountains skipped like rams, and the little hills like lambs.

Psalms 114:5 What ailed thee, O thou sea, that thou fleddest? thou Jordan, that thou wast driven back?

Psalms 114:6 Ye mountains, that ye skipped like rams; and ye little hills, like lambs?

These verses refer to how God miraculously delivered His people by parting the waters of the Red Sea and how He parted the waters of the Jordan River to allow them to cross over to begin taking possession of the Promised Land.  I’m not sure to what the reference to the mountains and hills refer unless there was an earthquake involved at those times.  Maybe it is referencing the time when God came down to meet the people from Mount Sinai, accompanied by lightning, thunder and smoke.  Maybe it is just the composer’s way of picturing how the creation rejoices when God displays His power over His creation.

Psalms 114:7 Tremble, thou earth, at the presence of the Lord, at the presence of the God of Jacob;

Psalms 114:8 Which turned the rock into a standing water, the flint into a fountain of waters.

The psalmist closes by calling for the earth to tremble at the presence of the LORD, the God of Jacob (Israel), the very same God that brought water from the rock to provide for His people. 

Exodus 17:6 “Behold, I will stand before thee there upon the rock in Horeb; and thou shalt smite the rock, and there shall come water out of it, that the people may drink. And Moses did so in the sight of the elders of Israel.”

And if the earth should tremble at such a display of God’s power, shouldn’t we!