Asalam alaykum wa rahmatuLLAH wa barakatuhu, I want to ask for expiation for someone who made a promise to build a mosque on a piece of land he owns but later changes his mind. He told one or two persons of his intention. May Almighty Allah increase His Rahman upon you.

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

The mere promise of building a mosque or declaring the intention to build one does not bind you to the promise, and nothing entails on you, neither expiation nor anything else.

What makes it necessary for a person to act upon and which he cannot go back is if he makes a vows that necessitates commitment, such as saying, 'I vow or I make an oath to Allah to build a mosque', and so on.

Allah knows best.