لَهُ دَعْوَةُ الْحَقِّ وَالَّذِينَ يَدْعُونَ مِنْ دُونِهِ لَا يَسْتَجِيبُونَ لَهُمْ بِشَيْءٍ إِلَّا كَبَاسِطِ كَفَّيْهِ إِلَى الْمَاءِ لِيَبْلُغَ فَاهُ وَمَا هُوَ بِبَالِغِهِ وَمَا دُعَاءُ الْكَافِرِينَ إِلَّا فِي ضَلَالٍ ﴿۱۴﴾

﴾14﴿ Lahoo da'watul haqq; wallazeena yad'oona min doonihee laa yastajeeboona lahum bishai'in illaa kabaasiti kaffaihi ilal maaa'i liyablugha faahu wa maa huwa bibaalighih; wa maa du'aaa'ul kaafireena illaa fee dalaal

﴾14﴿ Calling upon Allah alone is the true invocation. And those they invoke besides Allah cannot fulfill any of their needs. Their example is like someone who stretches out their hands toward water, hoping it will reach their mouth, but it does not reach them. And the supplication of the disbelievers is nothing but misguidance

[14] This verse is the conclusion of the previous evidences regarding the statement “To Him alone belongs the true call (دعوة الحق).” One interpretation is that “lahu” (to Him) is a fronted predicate for the sake of exclusivity, and the phrase “دعوة الحق” is a genitive construction where “دعوة” (the call) is the described and “الحق” (the truth) is the descriptor. That is, the true call belongs solely to Allah the Exalted, and calling upon anything besides Allah is falsehood.
The second meaning is that دعوة الحق refers to the call of monotheism (tawhid), and that this call is specific to Allah the Exalted, while the call of the polytheists is false. However, the first interpretation aligns more closely with the following part of the verse. This verse also refutes associating partners with Allah in supplication by way of a metaphor.
The core of the metaphor is as follows: imagine a person stretches out his hands toward water hoping that it will reach his mouth, and he calls out to the water. But the water cannot reach him. Similarly, the polytheist who calls out “help me!” to someone whom he believes, besides Allah, can fulfill his needs — while that being is either far away or dead — cannot hear the call, nor can he fulfill the need. Thus, the false deities are likened to water that cannot see, hear, or reach the person.
Another form of the metaphor is that of a thirsty person who sees a mirage and thinks it is water, then reaches out hoping to drink it, but the mirage cannot reach him because his assumption is false. Similarly, the polytheist believes that his false gods are real deities and asks them to fulfill his needs, but they cannot do so, and therefore his belief is invalid — because he has regarded something other than Allah as divine.
“And the prayer of the disbelievers is nothing but in vain (وَمَا دُعَاءُ الْكَافِرِينَ إِلَّا فِي ضَلَالٍ)” — this means that disbelievers ask for their needs from others besides Allah the Exalted. Such supplication is not true prayer; rather, it is shirk (polytheism) and misguidance. Another meaning is that disbelievers ask Allah for things, but their prayers are in vain — meaning they will not receive reward or divine response, even if they are occasionally answered in this world.