Maulana Wahiduddin Khan I Simple Wisdom I P.18   

It often happens in this world that man loses something or suffers some calamity. On such occasions, Islam teaches us to willingly resign ourselves to our misfortune, taking that to be God’s decree. On all such occasions the sufferer should utter the words: ‘Inna lillah wa inna ilayhi raji'un’ which means ‘We belong to God and to Him we shall return.’ (2:156)

God has made this world for the purpose of putting mankind to the test. Here, receiving and losing are both designed as a trial for man. Therefore, when man receives something, he should prove himself to be a thankful servant of God. And when he loses something, he should adopt the attitude of patience. Only one who can do so will pass God’s test.

In this world man cannot save himself from experiencing unpleasant things. Sometimes he will suffer from the pangs of hunger and thirst; at others, a life very dear to him will pass away or he will incur a loss of wealth. On all such occasions these words must come to his lips: ‘We belong to God and we shall all return to Him.’

Through these words man acknowledges his status of servitude vis-à-vis God’s all-powerfulness. He expresses himself in words such as these: O God, You are the giver. If You have taken something out of what You have given me, You had the right to do so.

Saying Inna lillah… is a form of worship. This is to adopt the attitude of surrendering to God’s will instead of complaining against fate. It is to convert the loss into a new discovery.

This phrase, ‘We are from God and to God we shall return’ is, in short, an acknowledgment of God’s godhead on the part of His servants.