Contradiction with Deuteronomy 20:16-17
These verses command the complete destruction of certain nations, including the Amorites, whereas Numbers 21:29 laments the fall of Moab.
Deuteronomy 20:16-17: But of the cities of these people, which the LORD thy God doth give thee [for] an inheritance, thou shalt save alive nothing that breatheth:
Contradiction with Matthew 5:44
This verse instructs to love your enemies, which contrasts with the mourning over Moab's defeat in Numbers 21:29.
Matthew 5:44: But I say unto you, Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you;
Contradiction with Hosea 2:23
This speaks of God having mercy and restoring people, whereas in Numbers 21:29, there is no indication of mercy or restoration for Moab.
Hosea 2:23: And I will sow her unto me in the earth; and I will have mercy upon her that had not obtained mercy; and I will say to [them which were] not my people, Thou [art] my people; and they shall say, [Thou art] my God.
Contradiction with Romans 12:19
Advises against seeking revenge, which contrasts with the theme of lament over conquest and destruction present in Numbers 21:29.
Romans 12:19: Dearly beloved, avenge not yourselves, but [rather] give place unto wrath: for it is written, Vengeance [is] mine; I will repay, saith the Lord.
Contradiction with Proverbs 24:17
This says not to rejoice when your enemy falls, contrasting with the tone of lamenting the defeated Moab in Numbers 21:29.
Proverbs 24:17: Rejoice not when thine enemy falleth, and let not thine heart be glad when he stumbleth: