From Bible.org:

This Arabic root means “to breathe heavy” (BDB 636, KB 688, Niphal PERFECT). This is an anthropomorphic metaphor. The root of this word expresses deep feelings (see Robert B. Girdlestone, Synonyms of the Old Testament, pp. 87-88). The prophet Nahum carries this term in his name. God is often spoken of in the Bible as changing His mind or relenting (cf. v. 6; Gen. 18:22-32; Num. 14:11-20; Josh. 7:6-13; II Kgs. 22:19-20; Ps. 106:45; Jer. 18:1-16; 26:3,13,19; Jonah 3:10). God is affected by (1) our prayers and (2) His character of compassion and love (cf. Exod. 3:7; Jdgs. 2:18; Hosea 11:8-9; Joel 2:13-14; Amos 5:15). However, this should not be understood in the sense that God’s nature or purpose vacillates. It does not change (cf. Num. 23:19; 1 Sam. 15:29; Mal. 3:6; Heb. 13:8; James 1:17).

Num. 23:19; 1 Sam. 15:29; Mal. 3:6; Heb. 13:8; James 1:17 are all used to override God changing His mind.