Charles H. Spurgeon on Psalms 36:10

O continue thy lovingkindness unto them that know thee. We ask no more than a continuance of the past mercy. Lord, extend this grace of thine to all the days of all who have been taught to know thy faithful love, thy tenderness, thine immutability and omnipotence. As they have been taught of the Lord to know the Lord, so go on to instruct them and perfect them. This prayer is the heart of the believer asking precisely that which the heart of his God is prepared to grant. It is well when the petition is but the reflection of the promise. And thy righteousness to the upright in heart. As thou hast never failed the righteous, so abide thou in the same manner their defender and avenger. The worst thing to be feared by the man of God is to be forsaken of heaven, hence this prayer; but the fear is groundless, hence the peace which faith brings to us. Learn from this verse, that although a continuance of mercy is guaranteed in the covenant, we are yet to make it a matter of prayer. For this good thing will the Lord be enquired of.