Abu Hurayrah (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "Whoever swears by Al-Lāt and Al-‘Uzza should say: 'there is no god but Allah'. Whoever says to his companion 'Come and gamble with me’ should give charity."
شرح الحديث :
The Prophet (may Allah's peace and blessings be upon him) ordered the person who swears by other than Allah, such as swearing by the pagan idols Al-Lāt and Al-‘Uzza or other than them, to declare the Oneness of Allah by saying: "There is no god but Allah". Moreover, he ordered the person who says to his companion: "I bet you that this is such-and-such" to give charity.