The ruling on one who vows to build a mosque if he possesses wealth

Question:
The third question: She says, “Several years ago, my husband swore an oath or made a vow that if he possessed two hundred thousand riyals, he would build a mosque. He has now possessed two million but has not built it. What is the ruling?” He is required to thank Allah.

Answer:
And to build the mosque, because the Messenger (peace be upon him) said . So if he vowed that if he possessed two hundred thousand he would build a mosque, and he now possesses two million, then Allah has multiplied his wealth for him, giving him the equivalent ten times over. It is obligatory for him to fulfill this vow and build the mosque. The Prophet (peace and blessings be upon him) said, “Whoever vows ,” and Allah praised the believers, saying, “They fulfill their vows.”