Sa'd bin 'Ubada Al-Ansari sought the verdict of Allah's Messenger (ﷺ) regarding a vow made by his mother who had died before fulfilling it. Allah's Messenger (ﷺ) said, "Fulfill it on her behalf." Some people said, "If the number of camels reaches twenty, then their owner has to pay four sheep as Zakat; and if their owner gives them as a gift or sells them in order to escape the payment of Zakat cunningly before the completion of a year, then he is not to pay anything, and if he slaughters them and then dies, then no Zakat is to be taken from his property."
Sahih al-Bukhari Book 90, Hadith 6
← Previous Hadith Allah's Messenger (ﷺ) said, "On the Day of Resurrection the Kanz (Treasure or wealth of which, Zakat has not been paid) of anyone of you will appear in the shape of a huge bald headed poisonous male snake and its owner will run away from it, but it will follow him and say, 'I am your Kanz.'" The Prophet (ﷺ) added, "By Allah, that snake will keep on following him until he stretches out his hand and let the snake swallow it." Allah's Messenger (ﷺ) added, "If the owner of camels does not pay their Zakat, then, on the Day of Resurrection those camels will come to him and will strike his face with their hooves." Some people said: Concerning a man who has camels, and is afraid that Zakat will be due so he sells those camels for similar camels or for sheep or cows or money one day before Zakat becomes due in order to avoid payment of their Zakat cunningly! "He has not to pay anything." The same scholar said, "If one pays Zakat of his camels one day or one year prior to the end of the year (by the end of which Zakat becomes due), his Zakat will be valid."

Sahih al-Bukhari Book 90, Hadith 5 Next Hadith → Nafi narrated to me that 'Abdullah said that Allah's Messenger (ﷺ) forbade the Shighar. I asked Nafi', "What is the Shighar?" He said, "It is to marry the daughter of a man and marry one's daughter to that man (at the same time) without Mahr (in both cases); or to marry the sister of a man and marry one's own sister to that man without Mahr." Some people said, "If one, by a trick, marries on the basis of Shighar, the marriage is valid but its condition is illegal." The same scholar said regarding Al-Mut'a, "The marriage is invalid and its condition is illegal." Some others said, "The Mut'a and the Shighar are permissible but the condition is illegal."

Sahih al-Bukhari Book 90, Hadith 7