It is narrated from Sa'id bin al-Harith that he heard Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) when a man from Banu Ka'b named Mas'ud bin Amr asked him: O Abu Abd al-Rahman! My son was in the land of Persia among those who were stationed with Umar bin Ubaydullah, and meanwhile a severe plague broke out in Basrah. When news of this reached me, I made a vow that if Allah Almighty brought my son back safe and sound, I would walk to the House of Allah. So he came back ill and then died. Now what is your view on this? Sayyiduna Ibn Umar (may Allah be pleased with them both) said: "Were you not forbidden from making vows? Indeed, the Messenger of Allah (peace and blessings be upon him) said: 'A vow neither brings anything (of destiny) forward before its time nor delays it; rather, it is only a means by which wealth is extracted from the miser.' Fulfil your vow." This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but the two Shaykhs did not record it with this wording and context.