Punishment is by Allah, and the Messenger's Job is only to convey the Message

Allah said to His Messenger ,

وَإِن مَّا نُرِيَنَّكَ

`(Whether We show you) O Muhammad, part of the disgrace and humiliation We have promised your enemies in this life,

أَوْ نَتَوَفَّيَنَّكَ

(or cause you to die) before that,

فَإِنَّمَا عَلَيْكَ الْبَلَـغُ

(your duty is only to convey We have only sent you to convey to them Allah's Message, and by doing so, you will have fulfilled the mission that was ordained on you,

وَعَلَيْنَا الْحِسَابُ

(and on Us is the reckoning), their reckoning and recompense is on Us.' Allah said in similar Ayat,

فَذَكِّرْ إِنَّمَآ أَنتَ مُذَكِّرٌ - لَّسْتَ عَلَيْهِم بِمُسَيْطِرٍ - إِلاَّ مَن تَوَلَّى وَكَفَرَ - فَيْعَذِّبُهُ اللَّهُ الْعَذَابَ الاٌّكْبَرَ - إِنَّ إِلَيْنَآ إِيَابَهُمْ - ثُمَّ إِنَّ عَلَيْنَا حِسَابَهُمْ

(So remind them - you are only one who reminds. You are not a dictator over them - Save the one who turns away and disbelieves. Then Allah will punish him with the greatest punishment. Verily, to Us will be their return, Then verily, for Us will be their reckoning.)88:21-26 Allah said next,

أَوَلَمْ يَرَوْاْ أَنَّا نَأْتِى الاٌّرْضَ نَنقُصُهَا مِنْ أَطْرَافِهَا

(See they not that We gradually reduce the land from its outlying borders.) Ibn `Abbas commented, "See they not that We are granting land after land to Muhammad ﷺ" Al-Hasan and Ad-Dahhak commented that this Ayah refers to Muslims gaining the upper hand over idolators, just as Allah said in another Ayah,

وَلَقَدْ أَهْلَكْنَا مَا حَوْلَكُمْ مِّنَ الْقُرَى

(And indeed We have destroyed towns round about you.) 46:27