Trust (tawakkul) is a cup sealed with Allah: none may drink from it or break the seal save the trustful. It is as Allah said,
On Allah should the trustful rely, (14:12)
On Allah should you rely if you are believers. (5:23)
Allah made trust the key of belief, and belief the lock of trust. The reality of trust is preferring others to oneself; the root of preferring others is to advance the other person’s claim. He who trusts continues to affirm one of two preferences in his trust. If he prefers what is caused (i.e. phenomenal being), he is veiled by it. If he prefers the Causer of the cause of trust (i.e. the Creator, glory be to Him and may He be exalted!), he remains with Him. If you want to be a man of trust and not a man of causes, then say the takbir over your ruh five times, and bid farewell to all your hopes as death bids farewell to life.
The lowest level of trust is nothing more than placing your highest aspiration before your own advancement; moreover, you should neither seek for your own portion nor look for what you lack, for either of those things would break the bond of your belief while you are unaware. If you are truly determined to live by one of the marks of the trusting one, and by His trust with respect to one of these two preferences, then cling to this story for support. It is related that one of the men of trust came to one of the Imams and said to him, ‘Show me compassion by answering a question about trust.’ The Imam knew the man to be of excellent trust and rare scrupulousness, and he saw his sincerity in what he was asking before the man actually put the question. ‘Stay where you are and wait with me for awhile,’ he told him. While he was formulating his answer a poor man passed by. The Imam put his hand into his pocket and, taking something out, gave it to the poor man. Then he turned to the man who had asked the question and said, ‘Come and ask about what you have seen.’ ‘O Imam,’ the man said, ‘I know that you could have given me the answer to my question before making me wait. Why then did you delay?’ And the Imam replied, ‘Belief means reflecting on the meaning before I speak. For how could I be negligent of my innermost being when my Lord perceives it? How could I discuss the science of trust while there is a coin in my pocket? It is not permitted for me to discuss that until after I had given it to him, so understand!’ The questioner sighed deeply and swore that he would not seek shelter in a house nor rely on another mortal as long as he lived.