It is narrated on the authority of Abu Umama that the Messenger of Allah (ﷺ) observed: He who appropriated the right of a Muslim by (swearing a false) oath, Allah would make Hell-fire necessary for him and would declare Paradise forbidden for him. A person said to him: Messenger of Allah, even if it is something insignificant? He (the Holy Prophet) replied: (Yes) even if it is the twig of the arak tree.

This hadith has been transmitted by another chain of narrators: Abu Bakr (RA) bin Abi Shaiba, Ishaq bin Ibrahim, Harun bin 'Abdullah, Abi Usama, Walid bin Kathir, Muhammad bin Ka'b, his brother 'Abdullah bin Ka'b and Abi Usama

Ka'b bin Malik reported: The Messenger of Allah (ﷺ) did not come back from the journey but by day in the forenoon, and when he arrived, he went first to the mosque, and having prayed two rak'ahs in it he sat down in it.

Ibn Ka'b bin Malik reported on the authority of his father that the Messenger of Allah (ﷺ) sent him and Aus bin Hadathan during the days of Tashriq to make this announcement: None but the believer would be admitted into Paradise, and the days of Mina' are the days meant for eating and drinking.

Abdullah bin Ka'ab bin Malik reported from his father that he pressed in the mosque Ibn Abu Hadrad for the payment of the debt that he owed to him during the lifetime of Allah's Messenger (ﷺ) . (In this altercation) their voices became loud, until Allah's Messenger (ﷺ) heard them, while he was in the house, so Allah's Messenger (ﷺ) came out towards them, and he lifted the curtain of his apartment and he called upon Ka'b bin Malik and said: O Ka'b. He said: At thy beck and call, Allah's Messenger. He pointed out with the help of his hand to remit half of the loan due to him. Ka'b said: Allah's Messenger, I am ready to do that, whereupon Allah's Messenger (ﷺ) said (to Ibn Abu Hadrad): Stand up and make him the payment (of the rest).

The above hadith is narrated through another chain with a slight variation of words at the begining and the rest is of the hadith is the same.

Ka'b bin Malik reported that he made a demand for the payment of the debt that Ibn Abu Hadrad owed to him. This hadith is narrated through another chain of transmitters and (the words are):" He had to get the loan from'Abdullah bin Hadrad al-Aslami. He met him and pressed him for payment. There was an altercation between them, until their voices became loud. There happened to pass by them Allah's Messenger (ﷺ) and he said: O Ka'b, and pointed out with his hand in such a way as he meant half. So he got half of what he (Ibn Abu Hadrad) owed to him and remitted the half."

'Abdullah bin Ka'b reported that his father Ka'b narrated to him that Allah's Messenger (ﷺ) used to eat with three fingers and when he had finished (eating), he licked them.

A hadith like this has been reported on the authority of Ka'b bin Malik through another chain of transmitters.

This hadith has been narrated through another chain, of transmitters also.'Abdullah bin 'Umar (RA) reported that Allah's Messenger (ﷺ) said: There is a tree amongst trees, the leaves of which do not wither and that is like a Muslim; tell me which that (tree) can be? The people began to think of the trees of the forest. 'Abdullah said: I thought that it could be the date-palm tree, but I felt hesitant (to say that). They (the Companions) then said: Allah's Messenger, (kindly) tell us which that can be? Thereupon he said: It is the date-palm tree. I made a mention of that to 'Umar, whereupon he said: Had you said that it meant the date-palm tree, this statement of yours (would have been dearer to me) than such and such things.'Abdullah bin 'Umar (RA) reported that Allah's Messenger (ﷺ) said: There is a tree amongst trees, the leaves of which do not wither and that is like a Muslim; tell me which that (tree) can be? The people began to think of the trees of the forest. 'Abdullah said: I thought that it could be the date-palm tree, but I felt hesitant (to say that). They (the Companions) then said: Allah's Messenger, (kindly) tell us which that can be? Thereupon he said: It is the date-palm tree. I made a mention of that to 'Umar, whereupon he said: Had you said that it meant the date-palm tree, this statement of yours (would have been dearer to me) than such and such things.

This hadith has been narrated on the authority of Ibn Ka'b through another chain of transmitters but with a slight variation of wording.