18 And he was sore athirst, and called on the LORD, and said, Thou hast given this great deliverance into the hand of thy servant: and now shall I die for thirst, and fall into the hand of the uncircumcised?
Soon Samson began to feel a fierce thirst; there was no water, and he could no longer stand to bear his thirst. Knowing that to attain human help would not be easy and that it would be difficult without divine aid, he called upon and begged almighty God. He did not think God would help him because of his offense against him, and because he had unwisely and carefully attributed any success to himself. No, he even assigned the victory to almighty God, saying, “You have given this very great deliverance into the hand of your servant, and it has been my help. And behold! Because I die of thirst, I am placed by my need of water into the power of those over whom you gave me a great triumph.” Then God’s mercy opened the earth when Samson threw down the jawbone, and a stream issued from it, and Samson drank and resumed his spirit and called the place “the invoking of the spring.” Thus, by his prayer, he atoned for his vaunting of victory.
Although we had been dried up because of lack of the dew of God’s grace, we merited to be changed into fountains and rivers. At that time Samson prayed and a fountain issued from the jawbone. This fact is clearly fulfilled in us, for the Lord himself said, “He who believes in me, from within him there shall flow rivers of living water.”
In the relics of the saints the Lord Christ has provided us with saving fountains which in many ways pour out benefactions and gush with fragrant ointment. And let no one disbelieve. For, if by the will of God water poured out of the precipitous living rock in the desert, and for the thirsty Samson from the jawbone of an ass, is it unbelievable that fragrant ointment should flow from the relics of the martyrs? Certainly not, at least for such as know the power of God and the honor which the saints have from him.
[AD 397] Ambrose of Milan on Judges 15:18-19