It is narrated from al-Hasan (may Allah have mercy on him) regarding a man who neglects zakah and Hajj until death comes to him. Al-Hasan (may Allah have mercy on him) used to say: Hajj and zakah are to be paid first. Then later he said: No, and there is no honour in it: he neglected it until, when the wealth was about to become someone else's, he said: Perform Hajj on my behalf and pay zakah on my behalf. It is from the third.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الوصايا / 12598
It is narrated from al-Hasan (may Allah have mercy on him) regarding a man who bequeaths that Hajj be performed on his behalf. He said: If he had already performed Hajj, the bequest will be fulfilled from the third; and if he had not performed Hajj, the Hajj will be performed from all his wealth, whether he made a bequest or not. It is a debt upon him.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الوصايا / 12599
Ibn Tawus narrates from his father (may Allah have mercy on them both) that when a man bequeaths something that was obligatory upon him, such as Hajj, the expiation for an oath or the expiation for zihar, it is to be taken from all his wealth.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الوصايا / 12600
It is narrated from al-Hasan (may Allah have mercy on him) regarding a man who bequeaths Hajj or zakah that it is from all his wealth.
It has been narrated to us from Ibrahim al-Nakha'i that he said: If he bequeaths Hajj or zakah, it is from the third, whether he had performed Hajj or not; and the like of that is narrated from Ibn Sirin. We hold the view of al-Hasan, Tawus, Ata and al-Zuhri, since they said that it is like a debt.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الوصايا / 12601
It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that a woman came to the Prophet (peace and blessings be upon him) and said: My mother vowed to perform Hajj, and she died before performing Hajj. Shall I perform Hajj on her behalf? He (peace and blessings be upon him) said: "Yes, perform Hajj. What do you think: if your mother had owed a debt, would you have paid it?" She said: Yes. He (peace and blessings be upon him) said: "Pay the debt of Allah, for fulfilling it is more deserving."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الوصايا / 12602