What did Moses name the altar he built after Israel defeated the Amalekites?

Moses built an altar after Israel defeated the Amalekites and called its name Jehovah Nissi, which the context explains means “I am your banner.” This appears in Exodus chapter 17, following the battle where Aaron and Hur held up Moses’ arms.

Les explains that this event comes in Exodus chapter 17, right after Israel had defeated the Amalekites while Aaron and Hur held up Moses’ arms. Moses then built an altar and named it Jehovah Nissi, which means “I am your banner.” The surrounding discussion also points to other compound names of Jehovah, including Jehovah Rapha, meaning the LORD who heals, and Jehovah Shalom, meaning peace.

Exodus 17

Who held up Moses' arms during the battle with the Amalekites?

So Her and Aaron held up Moses' arms during the battle with the Amalekites. After the victory, Moses built an altar and named it Jehovah Nissi, which means 'I am your banner.' This account is recorded in Exodus chapter 17.