Psalms 78 :7

That they might set their hope in God - That they might place confidence in God; that they might maintain their allegiance to him. The object was to give such exhibitions of his character and government as to inspire just confidence in him, or to lead people to trust in him; and not to trust in idols and false gods. All the laws which God has ordained are such as are suited to inspire confidence in him as a just and righteous ruler; and all his dealings with mankind, when they are properly - that is, "really" - understood, will be found to be adapted to the same end.

And not forget the works of God - His doings. The word here does not refer to his "works" considered as the works of creation, or the material universe, but to his acts - to what he has done in administering his government over mankind.

But keep his commandments - That by contemplating his doings, by understanding the design of his administration, they might be led to keep his commandments. The purpose was that they might see such wisdom, justice, equity, and goodness in his administration, that they would be led to keep laws so suited to promote the welfare of mankind. If people saw all the reasons of the divine dealings, or fully understood them, nothing more would be necessary to secure universal confidence in God and in his government.