God is not a man, that he should lie, nor a son of man, that he should change his mind. Does he speak and then not act? Does he promise and not fulfill? (Numbers 23:19)
Balaam, the false prophet was recruited by Balak, the Moabite king to curse Israel. But try as much as he would, Balaam was not able to curse the Israelites because God only gave words of blessing for him to pronounce. Initially, God did not want Balaam to go with the Moabite leaders to meet Balak, the king, but later seeing Baalam's eagerness, God allowed him to go but commanded him to speak only what God told him.
Balak was angry with Balaam for uttering words of blessing for the Israelites.
Balak said to Balaam, "What have you done to me? I brought you to curse my enemies, but you have done nothing but bless them!" He answered, "Must I not speak what the LORD puts in my mouth?" Then Balak said to him, "Come with me to another place where you can see them; you will see only a part but not all of them. And from there, curse them for me." So he took him to the field of Zophim on the top of Pisgah, and there he built seven altars and offered a bull and a ram on each altar. (Numbers 23:11-14)
The LORD met with Balaam and put a message in his mouth and said, "Go back to Balak and give him this message." Balak asked him, "What did the LORD say?" Balaam replied,
"God is not a man, that he should lie, nor a son of man, that he should change his mind. Does he speak and then not act? Does he promise and not fulfill? I have received a command to bless; he has blessed, and I cannot change it." (Numbers 23:19, 20)
No one's curse can harm you if God has decided to bless you. God will even bring words of blessing from the mouth of people who intend to curse you or have cursed you in the past. Our God is El Shaddai, Almighty God. Trust in him, he will never let you down. God bless you.