Explain Surah 4 (An-Nisa) verse 170 to me.

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

The verse that you wanted to be explained is the Saying of Allah: {O mankind! Verily, there has come to you the Messenger (Muhammad SAW) with the truth from your Lord, so believe in him, it is better for you. But if you disbelieve, then certainly to Allâh belongs all that is in the heavens and the earth. And Allâh is Ever All-Knowing, All­Wise.}[4:170].  Hafid Ibn Kathir said about its interpretation: '(meaning that the Prophet (Sallallahu Alaihi wa Sallam) has come to you with the guidance and the religion of the truth, and a cure from Allah, the Exalted.  So believe in what he has brought to you and follow him; it will be good for you.'

Then Allah Says (interpretation of meaning): {But if you disbelieve, then certainly to Allah belongs all that is in the heavens and the earth.} meaning that He does neither need your help nor your oaths, and He is not harmed by your becoming disbelievers, as Allah Says (interpretation of meaning): {And Mûsa (Moses) said: "If you disbelieve, you and all on earth together, then verily! Allâh is Rich (Free of all wants), Owner of all Praise."}[14:8].

And here Allah Says (interpretation of meaning): {And Allah is ever All-Knowing} meaning that whoever deserves guidance, Allah will guide him, and whoever deserves misguidance, Allah will misguide him: {All-Wise} meaning in his sayings and actions, His rule and predestination.

Allah knows best.