This a beneficail excerpt from the Speech of Sheikh Saalih Al-Fawzaan –may Allah preserve him- from his book Al-Irshaad ila Saheeh Al-'Itiqaad (An Indication to the Proper Belief) p.283 Daar Ibn Al-Jawzi print
2. From the fruits of Al-Eemaan (Faith) in The Divine execution of the Decree of Allah and the Pre-Determined Decree of Allah (القضاء و القدر) is security and ease of the heart and the absence of worrying in this (worldly) life after being exposed to the hardships of life. For indeed if the servant (of Allah) knows that what afflicts him is preordained and must occur and it cannot be prevented and he takes into consideration the statement of the Messenger, may the salutations and security be upon him, ((… what afflicts you is not meant to pass you and what passes you was not meant to afflict you…)), then surely this is when his soul becomes tranquil and his mind is at ease.
Contrary to the one who does not believe in the Divine execution of the Decree of Allah and Pre-Determined Decree of Allah. For certainly he is taken by worry, sadness, and is disturbed by anxiety until he becomes uninterested and dissatisfied with life and seeks to escape from it even by means of suicide. As it is seen from many of those who commit suicide whilst attempting to flee from the reality of their state of affairs and are pessimistic about their future being that they do not believe in the Divine execution of the Decree of Allah and Pre-Determined Decree of Allah. Therefore their action was the inevitable result of their evil creed.
Verily Allah the All Encompassing has said,
“No calamity befalls on the earth or in yourselves but it is inscribed in the Book of Decrees (Al-Lowh Al-Mahfoodh) before We bring it into existence. Verily, that is easy for Allah.” [057:022]
“In order that you may not grieve at the things over that you fail to get, nor over rejoice (arrogantly) in that which has been given to you. And Allah likes not every prideful boaster.” [057:023]
Therefore, Allah the One able to do all things has informed us that verily it is He who decrees what occurs from afflictions in the earth and within the (people) themselves. For this is decreed and written and is a must that it occurs, no matter how much we try to prevent it. Afterwards Allah made clear to us the wisdom in him informing us of this, (i.e. His Divine execution of His Decree and His Pre-Determined Decree), is for us to be tranquil and for us not to be anxious or regretful upon an affliction. And that we are not arrogantly joyful upon the occurring of a blessing, a joyfulness which causes us to forget the punishment of Allah. Rather it is obligatory upon us to be patient upon the afflictions and not to despair from the relief of Allah and (to have) thankfulness in affluence and not to feel secure from the plot of Allah and that we connect ourselves to Allah in these two conditions (the times of ease and hardship).
‘Ikrimah said:
“There is not a person that doesn’t feel happiness or sadness, so make your happiness thankfulness and your sadness patience.”
