Thou calledst in trouble - The people of Israel. Exodus 2:23; Exodus 3:9; Exodus 14:10.
And I delivered thee - I brought the people out of Egypt.
I answered thee in the secret place of thunder - That is, in the lonely, retired, solemn place where the thunder rolled; the solitudes where there was no voice but the voice of thunder, and where that seemed to come from the deep recesses of the mountain gorges. The allusion is doubtless to Sinai. Compare Exodus 19:17-19. The meaning is, that he gave a response - a real reply - to their prayer - amid the solemn scenes of Sinai, when he gave them his law; when he recognized them as his people; when he entered into covenant with them.
I proved thee - I tried you; I tested your fidelity.
At the waters of Meribah - Margin, as in Hebrew, strife. This was at Mount Horeb. Exodus 17:5-7. The trial - the proof - consisted in his bringing water from the rock, showing that he was God - that he was their God.