فَقَدْ كَذَّبُوكُمْ بِمَا تَقُولُونَ فَمَا تَسْتَطِيعُونَ صَرْفًا وَلَا نَصْرًا وَمَنْ يَظْلِمْ مِنْكُمْ نُذِقْهُ عَذَابًا كَبِيرًا ﴿۱۹﴾ وَمَا أَرْسَلْنَا قَبْلَكَ مِنَ الْمُرْسَلِينَ إِلَّا إِنَّهُمْ لَيَأْكُلُونَ الطَّعَامَ وَيَمْشُونَ فِي الْأَسْوَاقِ وَجَعَلْنَا بَعْضَكُمْ لِبَعْضٍ فِتْنَةً أَتَصْبِرُونَ وَكَانَ رَبُّكَ بَصِيرًا ﴿

﴾19﴿ Faqad kazzabookum bimaa taqooloona famaa tastatee'oona sarfanw wa laa nasraa; wa many yazlim minkum nuziqhu 'azaaban kabeeraa
﴾20﴿ Wa maaa arsalnaa qablaka minal mursaleena illaaa innahum la ya'kuloonat ta'aama wa yamshoona fil aswaaq; wa ja'alnaa ba'dakum liba'din fitnatan atasbiroon; wa kaana Rabbuka Baseera

﴾19﴿ (It will be said to them:) So they denied you regarding the words you used to say. Then you are not able to avert the punishment, nor to obtain any help. And whoever among you has done wrong, We shall make him taste a great punishment.
﴾20﴿ And We did not send before you any messengers except that they surely ate food and walked in the markets. And We have made some of you a trial for others—will you be patient? And your Lord is All-Seeing of everything.

[19] This is an address to the polytheists on the Day of Judgment. It means: you had claimed that these great figures had called you toward shirk, while these great ones denied it.
"Relief" refers to the prevention of punishment from themselves, and "assistance" means obtaining help from their deities.
"And whoever does wrong" refers to the Day of Judgment, and the present tense verb "does wrong" carries the meaning of the past tense, or this statement could also pertain to the worldly life.
[20] After describing the conditions of the Day of Judgment, the discourse returns to the objections of the deniers and their responses, as a form of warning.
This answers verse seven, meaning that eating food and walking in the markets—whether for worldly necessities or for the purpose of calling people to religion—does not contradict the mission of prophethood.
Then the reason for these objections is mentioned: this world is a place of trial. The sending of prophets is a test for the ignorant, as they raise objections against them. And the ignorant are a test for the prophets, who must show patience in the face of their criticisms and attacks.
Likewise, the wealthy and the poor are tests for each other, and the healthy and the sick are tests for one another.
"And your Lord is All-Seeing" means that Allah is fully aware and grants qualities to each person according to what suits them. So prophethood too has been granted to those who are suitable for it. Then why do you object to them?