Explanation

The meaning in a few plain lines

The Prophet (may Allah's peace and blessings be upon him) warned of swearing by other than Allah, for a believer should only swear by Allah. He informs that whoever swears by other than Allah, like someone who says: By Al-Lāt and Al-‘Uzza - two idols that used to be worshipped during the Jāhiliyyah (pre-Islam period of ignorance) - should hasten to correct himself by saying: There is no god but Allah. This is to disavow Shirk and expiate for such swearing. Then, he (may Allah's peace and blessings be upon him) informed that if someone says to his companion "Come and gamble with me" - when two or more persons compete with one another and the winner takes the money involved, and each one should necessarily win or lose - he is recommended to give something in charity, as expiation for what he has called for.