To put our trust on the Lord.
This is the crux of everything. David trusted the Lord and did not ask for any assurances as to his trust. How could it be otherwise? Wouldn't be hypocritical to ask for any assurances from Him? Of course it would be!
He put his trust in Him and believed in His provision for Him. This is truly remarkable.
This is real trust in God! An example for us all!