Tehillim 106:21

21 They forgot G-d their Moshi’a, Who had done gedolot in Mitzrayim;

Tehillim 106:21 Meaning and Commentary

Psalms 106:21

They forgat God their Saviour
Not only forgat the works of God, ( Psalms 106:13 ) , but forgat God that did those mighty works; forgat that there was a God; or however forgat him that is the only true and living God, when they said of the molten image, "these are thy gods, O Israel"; and what aggravated their crime was, they forgot that God that had saved them in so wonderful a manner out of the hand of their enemies, for his own name's sake; and had led them safely through the Red sea as on dry land, and destroyed those that hated them.

Which had done great things in Egypt:
meaning the ten plagues on the Egyptians, and the deliverance of the Israelites from them.

Tehillim 106:21 In-Context

19 They made an egel (a calf) in Chorev, and worshiped a massekhah (molden image).

20 Thus they exchanged their kavod for a tavnit shor (likeness of an ox) that eateth esev (grass).

21 They forgot G-d their Moshi’a, Who had done gedolot in Mitzrayim;

22 Nifla’ot (wondrous works) in Eretz Cham, and nora’ot (awesome things) by the Yam Suf.

23 Therefore He said that He would destroy them, had not Moshe His bechir (chosen one) stood before Him in the peretz (breach), to turn away His wrath, lest He should destroy them.