إِلاَّ بَلَغًا مِّنَ اللَّهِ وَرِسَالاَتِهِ
...
(Mine is) but conveyance from Allah and His Messages,
This is an exception related to the previous statement,
لَن يُجِيرَنِي مِنَ اللَّهِ أَحَدٌ
(None can protect me from Allah's punishment),
meaning, `nothing can save me from Him and rescue me except my conveyance of the Message that He has obligated me to carry out.'
This is as Allah says,
يَـأَيُّهَا الرَّسُولُ بَلِّغْ مَأ أُنزِلَ إِلَيْكَ مِن رَّبِّكَ وَإِن لَّمْ تَفْعَلْ فَمَا بَلَّغْتَ رِسَالَتَهُ وَاللَّهُ يَعْصِمُكَ مِنَ النَّاسِ
O Messenger!
Proclaim which has been sent down to you from your Lord. And if you do not, then you have not conveyed His Message. Allah will protect you from mankind. (5:67)
Then Allah says,
...
وَمَن يَعْصِ اللَّهَ وَرَسُولَهُ فَإِنَّ لَهُ نَارَ جَهَنَّمَ خَالِدِينَ فِيهَا أَبَدًا
and whosoever disobeys Allah and His Messenger, then verily, for him is the fire of Hell, he shall dwell therein forever.
meaning, `I will convey unto you all the Messages of Allah, so whoever disobeys after that, then his reward will be the fire of Hell wherein he will abide forever.'
This means, they will not be able to avoid it nor escape from it.
Then Allah says,
حَتَّى إِذَا رَأَوْا مَا يُوعَدُونَ فَسَيَعْلَمُونَ مَنْ أَضْعَفُ نَاصِرًا وَأَقَلُّ عَدَدًا