Lord knows you best; if He wills, He will have mercy on you, or if He wills, He will punish you. And We have not sent you as a guardian over them (54)And your Lord knows best all who are in the heavens and the earth. And indeed, We have preferred some of the Prophets above others, and to Dawud We gave the Zabur.) Allah say (55)

رَّبُّكُمْ أَعْلَمُ بِكُمْ

(Your Lord knows you best;) O mankind, meaning, He knows best who among you deserves to be guided and who does not deserve to be guided.

إِن يَشَأْ يَرْحَمْكُمْ

(if He wills, He will have mercy on you,) by helping you to obey Him and turn to Him.

أَوْ إِن يَشَأْ يُعَذِّبْكُمْ ۚ وَمَا أَرْسَلْنَاكَ

(or if He wills, He will punish you. And We have not sent you) - O Muhammad -

عَلَيْهِمْ وَكِيلًا

(as a guardian over them.) meaning, 'We have sent you as a warner, so whoever obeys you, will enter Paradise and whoever disobeys you, will enter Hell.'

وَرَبُّكَ أَعْلَمُ بِمَن فِي السَّمَاوَاتِ وَالْأَرْضِ

(And your Lord knows best all who are in the heavens and the earth.) meaning, their status or level of obedience or disobedience.

وَلَقَدْ فَضَّلْنَا بَعْضَ النَّبِيِّينَ عَلَىٰ بَعْضٍ

(And indeed, We have preferred some of the Prophets above others.) As Allah says:

تِلْكَ الرُّسُلُ فَضَّلْنَا بَعْضَهُمْ عَلَىٰ بَعْضٍ ۘ مِّنْهُم مَّن كَلَّمَ اللَّهُ ۖ وَرَفَعَ بَعْضَهُمْ دَرَجَاتٍ

(Those Messengers! We preferred some of them to others; to some of them Allah spoke (directly); others He raised to degrees (of honor.))[2:253]

This does not contradict the report in the Two Sahihs which says that the Messenger of Allah ﷺ said:

لَا تُفَضِّلُوا بَيْنَ الْأَنْبِيَاءِ

(Don't give superiority to any Prophet among (Allah's) Prophets.) What is meant in this Hadith is giving a superiority based on whims and fanaticism or sectarian feelings, not on the basis of evidence. If there is solid evidence, we have to follow it. There is no dispute that the Messengers are better than the rest of the Prophets, and that the mighty Messengers of Great Resolve are the best of all. They are the five mentioned in two Ayat of the Qur'an, in Surat Al-Ahzab:

وَإِذْ أَخَذْنَا مِنَ النَّبِيِّينَ مِيثَاقَهُمْ وَمِنكَ وَمِن نُّوحٍ وَإِبْرَاهِيمَ وَمُوسَىٰ وَعِيسَى ابْنِ مَرْيَمَ

(And (remember) when We took from the Prophets their covenant, and from you and from Nuh, Ibrahim, Musa and 'Isa son of Maryam.)[33:7] and in Surat Ash-Shura:

شَرَعَ لَكُم مِّنَ الدِّينِ مَا وَصَّىٰ بِهِ نُوحًا وَالَّذِي أَوْحَيْنَا إِلَيْكَ وَمَا وَصَّيْنَا بِهِ إِبْرَاهِيمَ وَمُوسَىٰ وَعِيسَىٰ ۖ أَنْ أَقِيمُوا الدِّينَ وَلَا تَتَفَرَّقُوا فِيهِ

(He has ordained for you the same religion which He ordained for Nuh, and that which We have revealed to you, and that which We ordained for Ibrahim, Musa and 'Isa saying you should establish religion and make no divisions in it.)[42:13]

There is no dispute that Muhammad ﷺ is the best of them, then Ibrahim, then Musa, then 'Isa (peace be upon them all), according to the best-known view. We have discussed the evidence for this in detail elsewhere, and Allah is the source of help. Allah's saying,

وَآتَيْنَا دَاوُودَ زَبُورًا

(and to Dawud We gave the Zabur.) is an indication of his virtue and honor. Al-Bukhari recorded from Abu Hurayrah that the Prophet ﷺ said:

خُفِّفَ عَلَى دَاوُدَ الْقُرْآنُ، فَكَانَ يَأْمُرُ بِدَوَابِّهِ فَتُسْرَجُ، فَكَانَ يَقْرَؤُهُ قَبْلَ أَنْ يَفْرُغَ

(The Qur'an (i.e. revea- led Scripture of Zabur) was made easy for Dawud, so he would call for his mounts to be saddled, and he would finish reciting it (i.e., the Zabur) be- fore the job was done.)