C. F. Keil and Franz Delitzsch on Judges 16:20

Jdg 16:20

She then cried out, “Philistines upon thee, Samson!” And he awaked out of his sleep, and thought (“said,” i.e., to himself), “I will go away as time upon time (this as at other times), and shake myself loose,” sc., from the fetters or from the hands of the Philistines; “but he knew not that Jehovah had departed from him.” These last words are very important to observe in order to form a correct idea of the affair. Samson had said to Delilah, “If my hair were cut off, my strength would depart from me” (Jdg 16:17). The historian observes, on the other hand, that “Jehovah had departed from him.” The superhuman strength of Samson did not reside in his hair as hair, but in the fact that Jehovah was with or near him. But Jehovah was with him so long as he maintained his condition as a Nazarite. As soon as he broke away from this by sacrificing the hair which he wore in honour of the Lord, Jehovah departed from him, and with Jehovah went his strength.“Samson was strong because he was dedicated to God, as long as he preserved the signs of his dedication. But as soon as he lost those signs, he fell into the utmost weakness in consequence. The whole of Samson’s misfortune came upon him, therefore, because he attributed to himself some portion of what God did through him. God permitted him to lose his strength, that he might learn by experience how utterly powerless he was without the help of God. We have no better teachers than our own infirmities.”-Berleb. Bible.