Oath or al-qasam a thing or habit of the Arabs in communicating to convince his interlocutors. The habits conducted by the Arab nation is a matter that the Qur'an was reconstructed and some have deconstructed the value and meaning. Therefore, the Qur'an was revealed in the Arab nation and also in Arabic, so God uses to communicate Kalam sworn in.
Even the customs in terms of the oath had been there since the value of Islamic doctrine unestablished order of the Arab nation. Although the Arabs known as idolatry (paganism) they still typically uses the word God in the oath, as pointed out by the Qur'an in surah Al Fathiir paragraph 42 which reads:
It means: "And they swear by Allah with all-powerful oath; Indeed, if it comes to them a warner, they will be guided from one's people (the other). when it comes to them a warner, so his arrival it does not increase them, except far they are from (the truth). "(QS. Al-Fathiir 35: 42)
Or in Surat an-Nahl verse 38, which reads:
Meaning:" They swear the name of God with earnest oath: "God will not raise the dead". (not so), even (surely Allah will raise it), as a true promises of God, but most people do not know ". (QS. An-Nahl 16: 38).
The term qasam According to the language to convey the same "al Hilf" and "al Yamin", but the charge meaning qasam firmer. The grammarians Arabic defines qasam with a sentence that has the function to reinforce a message. while louis ma'luf, qasam interpreted by swearing by God or others.
as for the notion qasam term can be explained as follows: