The שׁוּב presupposes that Samuel was about to go away after the executing his commission. Saul entreated him to remain that he might pray, i.e., not only in order to obtain for him the forgiveness of his sin through his intercession, but, according to 1Sa 15:30, to show him honour before the elders of the people and before Israel, that his rejection might not be known.
Verses 26-29
This request Samuel refused, repeating at the same time the sentence of rejection, and turned to depart. “Then Saul laid hold of the lappet of his mantle (i.e., his upper garment), and it tore” (lit. was torn off). That the Niphal ויּקּרע is correct, and is not to be altered into אתהּ ויּקרע, “Saul tore off the lappet,” according to the rendering of the lxx, as Thenius supposes, is evident from the explanation which Samuel gave of the occurrence (1Sa 15:28): “Jehovah hath torn the sovereignty of Israel from thee to-day, and given it to thy neighbour, who is better than thou.” As Saul was about to hold back the prophet by force, that he might obtain from him a revocation of the divine sentence, the tearing of the mantle, which took place accidentally, and evidently without any such intention on the part of Saul, was to serve as a sign of the rending away of the sovereignty from him. Samuel did not yet know to whom Jehovah would give it; he therefore used the expression לרעך, as רע is applied to any one with whom a person associates. To confirm his own words, he adds in 1Sa 15:29 : “And also the Trust of Israel doth not lie and doth not repent, for He is not a man to repent.” נצח signifies constancy, endurance, then confidence, trust, because a man can trust in what is constant. This meaning is to be retained here, where the word is used as a name for God, and not the meaning gloria, which is taken in 1Ch 29:11 from the Aramaean usage of speech, and would be altogether unsuitable here, where the context suggests the idea of unchangeableness. For a man's repentance or regret arises from his changeableness, from the fluctuations in his desires and actions. This is never the case with God; consequently He is ישׂראל נצח, the unchangeable One, in whom Israel can trust, since He does not lie or deceive, or repent of His purposes. These words are spoken θεοπρεπῶς (theomorphically), whereas in 1Sa 15:11 and other passages, which speak of God as repenting, the words are to be understood ἀνθρωποπαθῶς (anthropomorphically; cf. Num 23:19).
