Exodus 17:8-15 New American Standard Bible (NASB)
8 Then Amalek came and fought against Israel at Rephidim. 9 So Moses said to Joshua, “Choose men for us and go out, fight against Amalek. Tomorrow I will station myself on the top of the hill with the staff of God in my hand.” 10 Joshua did as Moses [a]told him, [b]and fought against Amalek; and Moses, Aaron, and Hur went up to the top of the hill. 11 So it came about when Moses held his hand up, that Israel prevailed, and when he let his hand [c]down, Amalek prevailed. 12 But Moses’ hands were heavy. Then they took a stone and put it under him, and he sat on it; and Aaron and Hur supported his hands, one on one side and one on the other. Thus his hands were steady until the sun set. 13 So Joshua [d]overwhelmed Amalek and his people with the edge of the sword.
14 Then the Lord said to Moses, “Write this in [e]a book as a memorial and [f]recite it to Joshua, [g]that I will utterly blot out the memory of Amalek from under heaven.” 15 Moses built an altar and named it The Lord is My Banner;
Exodus 17:8-15 New International Version (NIV)
The Amalekites Defeated
8 The Amalekites came and attacked the Israelites at Rephidim. 9 Moses said to Joshua, “Choose some of our men and go out to fight the Amalekites. Tomorrow I will stand on top of the hill with the staff of God in my hands.”
10 So Joshua fought the Amalekites as Moses had ordered, and Moses, Aaron and Hur went to the top of the hill. 11 As long as Moses held up his hands, the Israelites were winning, but whenever he lowered his hands, the Amalekites were winning. 12 When Moses’ hands grew tired, they took a stone and put it under him and he sat on it. Aaron and Hur held his hands up—one on one side, one on the other—so that his hands remained steady till sunset. 13 So Joshua overcame the Amalekite army with the sword.
14 Then the Lord said to Moses, “Write this on a scroll as something to be remembered and make sure that Joshua hears it, because I will completely blot out the name of Amalek from under heaven.”
15 Moses built an altar and called it The Lord is my Banner.