Psalm 78:16-18

David is drawing here on Numbers 21:4-6 and what they did is they disbelieved in God's mercy and goodness by presuming to tell Him what He should do and what He should give them. It was not, "Thy will be done." It was not humble and yielded, but they became impatient (like a child nagging his parents) by requiring unreasonable proofs from Him.

If you read through Psalm 78, over and over again He shows the proofs He gave these people that He loved them, that He cared for them, that He was providing for them, that He protected them, but they always wanted more. It was never enough. So they wanted unreasonable proofs of His presence, of His help, of His goodness, and all the while they really failed to try Him to supply their needs. What did they do? They took things into their own hands. That was always the end and they ended up sinning.

Psalm 78:17-22

So they did not delight in God, resulting in a limitation to God's blessing them. And they suffered greatly when they could have had a great blessing. The idea is that, in their minds, they set a limit to the power of God; by lying to themselves, they convinced themselves that there was a boundary to His power that He could not pass or that there were things that He could not perform. There is, somewhere in the Scriptures, I do not remember where it is, but it is where it calls Satan a liar who has deceived himself. And that is what these people had become—liars who had deceived themselves.