Lead me in thy truth, and teach me
Meaning the word of God, the Scriptures of truth; and the Gospel, which is the word of truth, and truth itself, ( John 17:17 ) ; and the sense is, either that God would lead him by his Spirit more and more into all truth, as contained in his word; or that he would lead him by it and according to it, that he might form his principles and his conduct more agreeably to it, which is the standard and rule of faith and practice: which leading is by teaching; and reasons urged for granting all the above petitions follow,
for thou [art] the God of my salvation;
who, in infinite wisdom, contrived scheme and method of it in his Son, and by him effected it, and by his Spirit had made application of it to him: and since the Lord had done such great things for him, he hoped the requests he had made would be granted: he adds,
on thee do I wait all the day;
or continually, in public and in private, attending to all the duties of religion, yet not trusting in them, but in the Lord; and therefore he entreated he might not be ashamed of his hope and expectation for deliverance and salvation.