the Holy House—meaning, in gratitude to Allah. The Prophet, peace and blessings be upon him, said, “Pray here.” The man asked him again, and he said, “Pray here.” When he asked him a third time, he said, “Then do as you wish.” (1) This shows that if one vows to perform it in the lesser mosque, it is permissible to perform it in the superior one, because it is more virtuous. But if he vows to perform it in the superior one, it is not permissible to perform it in the lesser one, because that falls short of the specification he made in his vow.
Shaykh al-Islam, may Allah have mercy on him, and some scholars cited this hadith as evidence that an endowment may be transferred from one purpose to another that is better than it. This is a clear line of reasoning, for a vow must be fulfilled. Thus, if the Prophet, peace and blessings be upon him, permitted a person to transfer a binding vow to what is superior, then an endowment—whose original basis is recommended—is even more deserving of this concession.
This applies to public endowments. As for private endowments, such as one made for a person’s children, it may not be transferred unless the line of descendants dies out, because a private endowment belongs specifically to those for whom it was established.
Whoever vows a specified period must enter his place of i‘tikāf before its first night and leave after its last day. A person observing i‘tikāf may leave only for something he cannot do without; he may not visit a sick person or attend a funeral unless he stipulates this.
His statement, “Whoever vows a specified period must enter his place of i‘tikāf before its first night and leave after its last day,” means, for example, that if he vows to observe i‘tikāf during the first ten days of Rajab, he enters at sunset on the last day of Jumada al-Akhirah.
If he vows to observe i‘tikāf during the last ten days of Ramadan, he enters at sunset on the twentieth day of Ramadan. This is why he said, “He must enter his place of i‘tikāf before its first night.”
He leaves when the sun sets on the final day of the period he specified.