There are five points to explain this question.
The First Sort of Supplication: This is the tongue of latent ability through which all seeds and grains supplicate to the All-Wise Creator saying: "Make us grow! Make our tiny truths sprout and transform us into the mighty reality of a tree so that we may display the elaborate embroideries of Your Names!"
A further sort of supplication through the tongue of latent ability is this: the gathering together of causes is a supplication for the creation of the effect. That is to say the causes acquire a position whereby they become like a tongue of disposition through which they supplicate for and request the effect from the All-Powerful One of Glory. For example water heat earth and light take up positions around a seed and their positions form a tongue of supplication which says: "O Our Creator make this seed into a tree!" For the tree which is a wonderful miracle of power cannot be attributed to those unconscious lifeless simple substances; it is impossible to attribute it to them. That means the coming together of causes is a sort of supplication.
The Second Sort of Supplication: This is through the tongue of innate need. It is a sort of supplication made by all living creatures to the All-Compassionate Creator to give them the things they need and desire which are beyond their power and will from unexpected places and at the appropriate time. For an the All-Wise and the Compassionate One sends them all these things at the right time from places they do not know beyond their power and will. Their hands cannot reach them. That is to say the bestowal is the result of supplication.
In Short: All that rises to the Divine Court from the universe is a supplication. Those things that are causes seek the effects from God.
The Third Sort of Supplication: This is the supplication of conscious beings arising from need. It is of two kinds.
If it is made at a time of desperate need or is completely conformable with innate need or if it is close to the tongue of latent ability or is made with the tongue of a pure sincere heart this supplication is virtually always acceptable. The greater part of human progress and most discoveries are the result of a sort of supplication. The things they call the wonders of civilization and the matters and discoveries they think are a source of pride are the result of what is in effect supplication. They were asked for with a sincere tongue of latent ability and so were given to them. So long as there is nothing preventing them and they are conformable with conditions supplications made through the tongue of latent ability and the tongue of innate need are always acceptable.
The Second Kind: This is the well-known supplication and it too is of two kinds. One is by action and the other by word. For example ploughing is a supplication by action. It is not seeking the sustenance from the earth rather the earth is a door to a treasury of mercy and the plough knocks on the earth the door to Divine Mercy.
We shall skip details of the remaining sorts and explain in the following two or three Points one or two of the secrets of supplication by word.
The effect of supplication is great. Especially if the supplication gains universality and persists it almost always has a result indeed its result is continuous. It may even be said that one of the reasons for the creation of the world was supplication. That is to say after the creation of the universe the supplications of chiefly mankind.
Since supplication possesses this great importance and capacity is it at all possible that the supplications offered all the time for thousands years by billions of mankind and by uncountable numbers of blessed beings from among men jinn angels and spirit beings for the All-Encompassing Divine Mercy eternal happiness and the accomplishment of their aims would not be accepted? Is it in any way possible that their supplications would be rejected?
Since these supplications have acquired universality extensiveness and continuousness to this extent and have reached the level of the tongues of latent ability and innate need for sure as a result of them the Great Messenger is at such a rank and degree that if all minds were to gather together and become one mind it could not completely comprehend it.
Sometimes supplications are offered for matters that are definite. Like for example the supplications in the prayers offered at the time of lunar and solar eclipses. Also sometimes supplications are made for things which will never come about?
As is explained in others of the Words supplication is worship. Through supplication the servant proclaims his own impotence and poverty. The apparent aim mark the times of the supplication and the supplicatory worship; they are not the true benefits. The benefits of worship look to the hereafter. If the worldly aims are not obtained it may not be said: "The supplication was not accepted." It should rather be said: "The time for the supplication has still not ended."
Also is it at all possible that eternal happiness which all the believers have asked for at all times continuously with complete sincerity and yearning and entreaty should not be given to them and that the Absolutely Generous One the Absolutely Compassionate One. Who according to the testimony of all the universe possesses boundless mercy should not accept their supplications and that eternal happiness should not exist?
There are two ways in which voluntary supplication by word is acceptable. It is either accepted exactly as desired or what is better is granted.
For example someone asks for a son and the Almighty God gives a daughter like Mary mother of Jesus. It may not be said: "His supplication was not accepted." but that "It was accepted in a better form."
Also sometimes a person makes supplication for his own happiness in this world and it is accepted for the hereafter. It may not be said: "His supplication was rejected." but that "It was accepted in a more beneficial form." And likewise since the Almighty God is the All Wise we seek from Him and He responds to us. But He deals with us according to His Wisdom.
A sick person should not cast aspersions on the wisdom of his doctor. If he asks for honey and the expert doctor gives him quinine he may not say: "The doctor did not listen to me." Rather the doctor listened to his sighs and moans; he heard them and responded to them. He provided better than what was asked for.
The best finest sweetest most immediate fruit and result of supplication is this that the person who offers it knows there is someone who listens to his voice sends a remedy for his ailment takes pity on him and whose hand of power reaches everything. He is not alone in this great hostel of the world; there is an All-Generous One Who looks after him and makes it friendly. Imagining himself in the presence of the One Who can bring about all his needs and repulse all his innumerable enemies he feels a joy and relief; he casts off a load as heavy as the world and exclaims: "All praise be to God the Sustainer of All the Worlds!"
Supplication is the spirit of worship and the result of sincere belief. For one who makes supplication shows through it that there is someone who rules the whole universe; One Who knows the most insignificant things about me can bring about my most distant aims. Who sees every circumstance of mine and hears my voice. In which case. He hears all the voices of all beings so that He hears my voice too. He does all these things and so I await my smallest matters from Him too. I ask Him for them.
Thus look at the great breadth of sincere belief in God's Unity which supplication gives and at the sweetness and purity of the light of belief that it shows. Understand the meaning of the verse. "Say. No importance would your Sustainer attach to you were it not for your supplication (25:77)"; Listen to the decree of. And your Sustainer says: "Call on Me; I shall answer you (40:60)".
As the saying goes: "If I had not wanted to give. I would not have given wanting."