Hazrat Moulana Ashraf Ali Thaanwi (rahimahullah) once mentioned the following:
In today’s times, the condition of people is quite strange. If a person does any pious deed, then he begins to wait for ilhaam or wahi (divine inspiration or revelation), thinking to himself that perhaps he will hear a voice from the sky (informing him that his action is accepted), or if he makes du‘aa for some worldly need to be fulfilled, then he begins to wait for a sign showing him that his du‘aa is answered. How foolish indeed is this attitude!
Nabi Moosa (‘alaihis salaam) made du‘aa to Allah Ta‘ala against Fir‘aun (that Allah Ta‘ala punish him), and Allah Ta‘ala even informed Nabi Moosa (‘alaihis salaam) and Nabi Haaroon (‘alaihis salaam) that both their du‘aas had been accepted. However, the outcome of the acceptance of this du‘aa was only seen forty years later.
It is a sign of a person’s boldness and feeling over-confident that he makes du‘aa, and then expects to see immediate results. This was not even experienced by the Ambiyaa (‘alaihimus salaam), even though they were such that their du‘aas were always accepted (i.e. they did not always see the outcome of their du‘aas materialize immediately).
(Malfoozaat Hakeemul Ummat 1/79-80)
Source: Ihyaauddeen.co.za