Ibn Hibban

Saeed bin Harith narrates: I was present with Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) when a man came to him and said: O Abu Abdur Rahman! My son was in the land of Persia, where a plague spread. I made a vow that if Allah Almighty saved my son, he would go to the Ka'bah on foot. Then my son (returned alive and safe), but he passed away. So Sayyiduna Abdullah (may Allah be pleased with him) said to him: Fulfill your vow. The man said to him: I had vowed that my son would go on foot, but my son has passed away. Sayyiduna Abdullah (may Allah be pleased with him) became angry and said: Were you not forbidden from making vows? I heard the Prophet (peace and blessings of Allah be upon him) say: "Indeed, a vow does not bring anything forward or delay it, but Allah, through it, extracts wealth from the miser." (The narrator says) When I saw this situation, I said to that man: Go to Saeed bin Musayyib and ask him about this issue. He went to him and asked about this issue. Then he returned, so I asked: What answer did he give you? He said: He told me: Go on foot on behalf of your son. He asked: Is this permissible for me? So Saeed bin Musayyib said: What do you think, if your son had a debt and you paid it off, would it be considered paid on his behalf? I replied: Yes. So he said: Go on foot on behalf of your son.