Psalms 106:7

Our fathers understood not - They did not regard the operation of God's hands; and therefore they understood neither his designs nor their own interest.

At the sea, even at the Red Sea - Some of the rabbins suppose that the repetition of the words point out two faults of the Israelites at the Red Sea.

1. They murmured against Moses for bringing them out of Egypt, when they saw the sea before them, and Pharaoh behind them.

When the waters were divided, they were afraid to enter in, lest they should stick in the mud which appeared at the bottom.

The word seems to be added by way of explanation, and perhaps may refer to the above: they provoked ים על al yam , "At the sea;" סוף בים beyam suph , "In the sea Suph," or Red Sea. They provoked him at it and in it.