Say: "Tell me! If Allah destroys me, and those with me, or He bestows His mercy on us - who can save the disbelievers from a painful torment? (28)Say: "He is the Most Gracious, in Him we believe, and upon Him we rely. So, you will come to know who it is that is in manifest error. (29)Say: "Tell me! If (all) your water were to sink away, who then can supply you with flowing water? (30)

The Death of the Believer will not save the Disbeliever, so let Him reflect upon His Deliverance

Allah says,

قُلْ 

(say) 'O Muhammad to these idolators who are associating partners with Allah and denying His favors,'

أَرَأَيْتُمْ إِنْ أَهْلَكَنِيَ اللَّهُ وَمَنْ مَعِيَ أَوْ رَحِمَنَا فَمَنْ يُجِيرُ الْكَافِرِينَ مِنْ عَذَابٍ أَلِيمٍ

(Tell me! If Allah destroys me, and those with me, or He bestows His mercy on us - who can save the disbelievers from a painful torment?) meaning, 'save yourselves, for verily, there is nothing that can rescue you from Allah except repentance, turning to Him for forgiveness and returning to His religion. Your hopes that torment and exemplary punishment will strike us, will not benefit you. Whether Allah punishes us or has mercy on us, there is no escaping from Allah's punishment and painful torment that you will suffer.' Then Allah says,

قُلْ هُوَ الرَّحْمَٰنُ آمَنَّا بِهِ وَعَلَيْهِ تَوَكَّلْنَا ۖ 

(Say: "He is the Most Gracious, in Him we believe, and upon Him we rely.) meaning, 'we believe in the Lord of all that exists, the Most Gracious, the Most Merciful, and upon Him we rely in all of our affairs.' This is as Allah says,

 فَاعْبُدْهُ وَتَوَكَّلْ عَلَيْهِ

(So worship Him and rely upon Him.)(11:123) Thus, Allah continues saying,

فَسَتَعْلَمُونَ مَنْ هُوَ فِي ضَلَالٍ مُبِينٍ

(So, you will come to know who it is that is in manifest error.) meaning, 'between Us and you, and to whom the final end (ultimate victory) will be for in this life and in the Hereafter.'

Reminding of Allah's Blessing by the springing of Water and the Threat of It being taken away

Allah says;

قُلْ أَرَأَيْتُمْ إِنْ أَصْبَحَ مَاؤُكُمْ غَوْرًا 

(Say: "Tell me! If your water were to sink away...") meaning, if it were to go away, disappearing into the lowest depths of the earth, then it would not be reachable with iron axes nor strong arms. 'Gha'ir' (sinking) as used here in the Ayah, is the opposite of springing forth. This is why Allah says,

فَمَنْ يَأْتِيكُمْ بِمَاءٍ مَعِينٍ

(who then can supply you with flowing water?) meaning, springing forth, flowing, running upon the face of the earth. This means that no one is able to do this except Allah. So, it is merely out of His favor and His grace that He causes water to spring forth for you, and He makes it run to the various regions of the earth in an amount that is suitable for the needs of servants, be it little or abundant. So Allah's is all the praise and thanks.

This is the end of the Tafsir of Surat Al-Mulk and all praise and thanks are due to Allah.