"And if only they were satisfied with what God and His Messenger have given them"—meaning: what He has bestowed upon them of His bounty.

He means: from the bounty of God. "And said, 'Sufficient for us is God; God will give us out of His bounty and [so will] His Messenger'"—to the end of the verse. It is also read as: "wa rasulahu" (and His Messenger) in the accusative case; meaning: He will give to His Messenger.

There is an ellipsis in it; meaning: it would have been better for them than the hypocrisy they manifested.