ibn Umar · The Book of Oaths

He who has to take an oath, he must not take oath but by Allah. The Quraish used to take oath by their fathers. So he (the Holy Prophet) said: Do not take oath by your fathers.

Messenger of Allah, I had taken a vow during the days of Ignorance (Jahiliyya) that I would observe I'tikaf for a night in the Sacred Mosque. He (the Holy Prophet) said: Fulfil your vow.

When Allah's Apostle (ﷺ) came back from the Battle of Hunain, Umar asked Allah's Messenger (ﷺ) about the vow he had taken during the days of Ignorance that he would observe I'tikaf for a day. The rest of the hadith is the same.

When a slave looks to the welfare of his master and worships Allah well, he has two rewards for him.

He who gives up his share in a slave, and has enough money to pay the full price of the slave, then full emancipation devolves upon him; but if he has not the money, then he emancipated what he emancipated.

He who emancipates his share in the slave, it is his responsibility to secure full freedom for him provided he (the slave) has enough money to pay the (remaining) price, but it he has not so much money he would be emancipated to the extent that the first man emancipated.

He who gives up his share in a slave, the remaining (share) will be paid out of his riches if his riches are enough to meet the price of the slave.