Boaz married a Moabite woman (Ruth), and their son (Obed) was the father of Jesse and the grandfather of David.
Boaz took Ruth, and she was his wife: and when he went in unto her, the LORD gave her conception, and she bare a son. ... Tthey called his name Obed: he is the father of Jesse, the father of David. Ruth 4:13-17
Ezra was so upset when he heard that the Isralites were marrying Moabites (among others) that he rent his garment and mantle, plucked out the hair of his head and beard, and sat down astonished.
The princes came to me, saying, The people of Israel, and the priests, and the Levites, have not separated themselves from the people of the lands, doing according to their abominations, even of ... the Moabites. ... For they have taken of their daughters for themselves, and for their sons: so that the holy seed have mingled themselves with the people of those lands. ... And when I heard this thing, I rent my garment and my mantle, and plucked off the hair of my head and of my beard, and sat down astonished. Ezra 9:1-3
Nehemiah was also upset by Israelites marrying wives from Moab; so upset, in fact, that he cursed all of them, smote some of them, and plucked off their hair, and made them swear not to give their daughters to Moabite sons, or take Moabite daughters for themselves or their sons.
In those days also saw I Jews that had married wives ... of Moab. ... And I contended with them, and cursed them, and smote certain of them, and plucked off their hair, and made them swear by God, saying, Ye shall not give your daughters unto their sons, nor take their daughters unto your sons, or for yourselves. .... Shall we then ... do all this great evil, to transgress against our God in marrying strange wives? Nehemiah 13:23-27