Iddat  

In the name of Allah, We praise Him, seek His help and ask for His  forgiveness. Whoever Allah guides none can misguide, and whoever He allows to fall astray, none can guide them aright. We bear witness that there is no one (no idol,  no person,  no grave, no prophet,  no imam,  no dai,  nobody!) worthy of worship but Allah Alone, and we bear witness that Muhammad(saws) is His slave-servant and the seal of His Messengers.

Allah says in the Holy Quran Chapter 2 Surah Baqarah verse 234:

If those of you,  who die,  leave wives behind;  they should abstain (from marriage) for four months and ten days.   Then,  when their waiting term expires,  they are free to do whatever they choose for themselves,  provided that it is decent.   You shall not be answerable for this.   Allah is fully aware of what all of you do.

Thus the reason a woman,  who truly believes in Allah and the Last Day,  must sit in ‘iddat’ for the prescribed period because it is the command of Allah Subhanah.   And we as believers must believe that each and every command of Allah is based on His Perfect Knowledge and Wisdom.

We are also allowed to search and understand the wisdom,  so that we may be able to obey every command of our Lord and Creator wholeheartedly.   The main reasons for this waiting period are:

1. When the woman performs the waiting period of four months and ten days as commanded by Allah,  it will become absolutely clear if the woman is indeed pregnant or not.    This pregnancy will effect the inheritance as well as the legal basis of the baby.
2. During this period,  the woman is advised to abstain from any sort of display of happiness and celebration, and to mourn the death of her life-partner.   
3. This period decreed by Allah will also allow the woman to cope emotionally with the huge loss that she has suffered. 
4. It will  also be a means of huge reward and ‘ajr’ from Allah Subhanah when the widow obeys this command from Allah in honor of her dead husband.

Whatever written of Truth and benefit is only due to Allah’s Assistance and Guidance, and whatever of error is of me.  Allah Alone Knows Best and He is the Only Source of Strength.

Your brother and well wisher in Islam,