1 Samuel 15:2

Thus saith the Lord of hosts
Of the celestial host of angels, and of the army of Israel, yea, of all the armies of the earth: this is premised to engage the attention of Saul:

I remember that which Amalek did to Israel;
four hundred years ago:

how he laid wait for him in the way when he came up from Egypt;
in the valley of Rephidim, just before they came to Mount Sinai, and fell upon the rear of them, and smote the feeble, and faint, and weary, see ( Exodus 17:8 ) ( Deuteronomy 25:17-19 )