Ulum al Qur'an
Oaths in the Qur’an
In a number of places the Qur'an employs oath-like expressions (aqsdm, sg. qasam). [For a brief discussion see also Abdullah Yusuf Ali, op. cit., App. XIV, pp. 1784-7.] Their function is to strengthen and support an argument, and to disperse doubts in the mind of the listener. In the Arabic text these passages are often opened by the word 'wa' or the phrase 'la uqsimu' (indeed I swear).
Examples:
Sometimes an oath is taken by Allah himself:
'But no, by thy Lord, they can have no real faith until they make thee judge in all disputes between them and find in their souls no resistance against thy decisions but accept them with fullest conviction' (Al-Qur'an 4: 65).
Other oaths are taken by Allah's creation:
'By the sun and his (glorious) splendour, by the moon as she follows him, by the day as it shows up (the sun's) glory, by the night as it conceals it; by the firmament and its (wonderful) structure, by the earth and its (wide) expanse, by the soul and the proportion and order given to it ...' (Al-Qur'an 91: 1-7).
'I do call to witness this city ...' (Al-Qur'an 90: 1).
Man should only take an oath bv Allah the creator. but not by anything created.