َ قُلْ هُوَ الرَّحْمَنُ آمَنَّا بِهِ وَعَلَيْهِ تَوَكَّلْنَا فَسَتَعْلَمُونَ مَنْ هُوَ فِي ضَلَالٍ مُبِينٍ ﴿۲۹﴾ قُلْ أَرَأَيْتُمْ إِنْ أَصْبَحَ مَاؤُكُمْ غَوْرًا فَمَنْ يَأْتِيكُمْ بِمَاءٍ مَعِينٍ

﴾29﴿ Qul huwar rahmaanu aamannaa bihee wa 'alaihi tawakkalnaa fasata'lamoona man huwa fee dalaalim mubeen
﴾30﴿ Qul ara'aytum in asbaha maaa'ukum ghawran famai ya'teekum bimaaa'im ma'een

﴾29﴿ Say, He is the Most Merciful; we have believed in Him, and upon Him we have relied. Soon you will know who is in clear error
﴾30﴿ Say, Consider this: if your water were to sink into the earth, then who could bring you flowing water

[30] This too is a silent, confessional proof, and it mentions a form of warning—using the example of a punishment, which is the drying up of water.
(غَوْرًا) – Refers to water that sinks deep into the earth and dries up in such a way that it cannot be retrieved, even by digging.
The intended meaning of this water is springs, wells, and rivers.
(مَعِينٍ) – This is either the passive form (maf‘ūl) from ‘ayn, meaning visible water that the eye can see, or the active form (fa‘īl) from ma‘n, meaning abundant flowing water—like that of springs, and it is also used for fresh water.
The answer to this rhetorical question (from the side of the polytheists) is clear: Allah the Exalted alone can cause this water to disappear.
And since there are many divine blessings in water, it becomes evident that the only giver of blessings is Allah the Exalted.