Concise Bible Dictionary:
Ben-ammi was the son of Lot by his youngest daughter. “The same is the father of the children of Ammon” (Gen. 19:38). His descendants were neighbors to Israel between the Arnon and the Jabbok on the east, and had much to do with Israel. God had bidden Moses not to touch the Ammonites, nor was their land to be possessed by Israel: it had been given to the children of Lot. Their city was Rabbath-ammon, perhaps their only city, as they were a nomadic people. None of the nation were to be allowed to enter the congregation of Israel to the tenth generation, that is, forever (Deut. 23:3; Neh. 13:1). With Amalek they assisted the king of Moab against Israel, and Jericho fell into their hands (Judg. 3:13). Israel served their gods, and God gave them up on both sides of the Jordan to serve the Ammonites. On Israel crying to Jehovah the children of Ammon were defeated under Jephthah. In the early days of Saul’s reign they besieged Jabesh-gilead, and would only make peace on the condition that the right eyes of the inhabitants should be thrust out, in order that it might be a reproach on Israel; but Saul hastened to their aid, and routed the Ammonites (1 Sam. 11:1-11; 1 Sam. 12:12). Their gold and silver taken in battle were dedicated by David to Jehovah. Their king insulted David’s servants sent to show kindness to him, as the world refuses the kindness of God’s king, and brings judgment upon it (2 Sam. 10:1-10; 2 Sam. 11:1; 2 Sam. 12:26-31).
On the other hand, Shobi, of Rabbah, brought provisions when David fled from Absalom (2 Sam. 17:27), and Zelek, an Ammonite, was one of David’s thirty valiant men. Solomon loved some of their women, and the mother of his son Rehoboam was Naamah an Ammonitess (1 Kings 14:21, 31). They molested Israel with varied success until the days of Jehoiakim (2 Kings 24:2). Lot being the father of both Moab and Ammon, it is not surprising that the Moabites were often linked with the Ammonites in their attacks upon Israel. Hatred of God’s people united them in one common desire to cut them off from being a nation (Psalm 83:4-8). Tobiah, an Ammonite, was a troublesome adversary to the Jews on their return from captivity. (Neh. 2:10,19; Neh. 4:3,7). Nevertheless the Jews intermarried with this nation, thus mixing “the holy seed” with the people of the land. (Ezra 9:1-2; Neh. 13:23-25).
The whole history supplies us with instruction as to the imperative necessity of keeping separate from the contaminations of the world in order to walk with God, and be blessed by Him.
When the king of the north, in a future day, shall enter into “the glorious land,” Edom, Moab, and Ammon shall escape his hand (Dan. 11:41); they are reserved to be subdued by Israel, whom they seduced and persecuted in by-gone ages (Isa. 11:14).
Milcom and Molech were the gods of the Ammonites: to the worship of which Solomon had been seduced by his strange wives (1 Kings 11:5,7).