Charles Ellicott Commentary Deuteronomy 25:17-19

"Remember what Amalek did unto thee by the way as ye came forth out of Egypt; how he met thee by the way, and smote the hindmost of thee, all that were feeble behind thee, when thou wast faint and weary; and he feared not God. Therefore it shall be, when Jehovah thy God hath given thee rest from all thine enemies round about, in the land which Jehovah thy God giveth thee for an inheritance to possess it, that thou shalt blot out the remembrance of Amalek from under heaven; thou shalt not forget." — Deuteronomy 25:17-19 (ASV)

Deuteronomy 25:17–19. AMALEK TO BE EXTERMINATED.

At the end of all the precepts of humanity, the extermination of those people who are presented to us as the incarnation of inhumanity is decreed.

(Deuteronomy 25:18) He ... smote the hindmost ... — These details are not given in Exodus 17. Amalek’s attack followed the appearance of the stream of water from Horeb. It was only natural that the faint and weary would stay behind at the water side. There the Amalekites appear to have found them and cruelly massacred them.

Thou shalt blot out the remembrance of Amalek. — This decree was entrusted to Joshua in the first instance, as the “servant of the Book” (Exodus 17:14); here it is enjoined upon the nation of Israel.

It was carried out in several stages: by Barak and Gideon (Judges 5:14; Judges 6:3; Judges 7:12, and others), by Saul and Samuel (1 Samuel 15), by David (1 Samuel 27:8–9; 1 Samuel 30:17), by the Simeonites (1 Chronicles 4:42–43), and lastly by Esther, who exterminated the Agagites in Haman’s house. No doubt any remnant of Amalek in the Persian empire under Mordecai would have shared Haman’s fate.