Taking a Qasm (Oath) in the name of Allah Ta’ala has become all too common in these days. Qasms are taken for almost anything and everything, and often, over trivial matters – so much so that many take a Qasm and lie – (Na`uzu Billahi min zaalik)
What has happened, is that we have ‘reduced’ the greatness of taking a Qasm in the name of Allah Ta’ala.
A Qasm should only be taken if necessary.
Taking a Qasm is not to be treated in the light hearted manner that we do, or as a joke – that any little thing or on petty and silly issues, a person utters some oath, and sometimes many, many times in a day. It becomes a mockery of the name of Allah Ta’ala.
If a person has to break an oath or do something contrary to his oath, then he will have to give ‘kaffarah’. 
§ Kaffarah comprises of feeding 10 persons with two meals each. Alternatively, he could give some dry groceries to each poor person.
§ He also has the option of giving some clothing to 10 poor persons. The clothing must be such that it can cover a major portion of the poor person’s body.
§ If a person is poor and is unable to fulfill the requirements of Kaffarah, he will have to fast for 3 days consecutively.
 Na-oozu Billahi min zaalik : We seek Allah’s protection from that.
 It is a major sin to take an oath in the name of anyone other than Allah Ta’ala.
 There are many more masaa`il (rules) relating to Oaths, Vows and Kaffarah. Refer to the Beheshti Zewar or a reliable kitaab of Jurisprudence or find out details from an Aalim.
By Hazrat Maulana Yunus Patel Saheb (Rahmatullahi ‘alayh)