نَحْنُ أَعْلَمُ بِمَا يَقُولُونَ
We know best what they say.
means, `Our knowledge is all encompassing of the denial that the idolators are confronting you with, so do not be concerned.'
In similar Ayat, Allah said,
وَلَقَدْ نَعْلَمُ أَنَّكَ يَضِيقُ صَدْرُكَ بِمَا يَقُولُونَ
فَسَبِّحْ بِحَمْدِ رَبِّكَ وَكُنْ مِّنَ السَّـجِدِينَ
وَاعْبُدْ رَبَّكَ حَتَّى يَأْتِيَكَ الْيَقِينُ
Indeed, We know that your breast is straitened at what they say. So glorify the praises of your Lord and be of those who prostrate themselves (to Him). And worship your Lord until there comes unto you the certainty (i.e., death). (15;97-99)
Allah's statement,
وَمَا أَنتَ عَلَيْهِم بِجَبَّارٍ
And you are not the one to force them.
says, `it is not you who forces them to accept the guidance; this is not a part of your mission.'
Allah the Exalted and Most Honored said,
فَذَكِّرْ بِالْقُرْانِ مَن يَخَافُ وَعِيدِ
But warn by the Qur'an; him who fears My threat.
meaning, `convey the Message of your Lord, for only those who fear Allah and dread His torment, and hope in His promise will remember and heed,'
فَإِنَّمَا عَلَيْكَ الْبَلَـغُ وَعَلَيْنَا الْحِسَابُ
Your duty is only to convey (the Message) and on Us is the reckoning. (13;40),
فَذَكِّرْ إِنَّمَأ أَنتَ مُذَكِّرٌ
لَّسْتَ عَلَيْهِم بِمُسَيْطِرٍ
So remind them -- you are only one who reminds. You are not a dictator over them. (88;21-22)
لَّيْسَ عَلَيْكَ هُدَاهُمْ وَلَـكِنَّ اللَّهَ يَهْدِى مَن يَشَأءُ
Not upon you is their guidance, but Allah guides whom He wills. (2;272)
and,
إِنَّكَ لَا تَهْدِى مَنْ أَحْبَبْتَ وَلَـكِنَّ اللَّهَ يَهْدِى مَن يَشَأءُ
Verily, you guide not whom you like, but Allah guides whom He wills. (28;56)
Allah's statement here,
وَمَا أَنتَ عَلَيْهِم بِجَبَّارٍ
فَذَكِّرْ بِالْقُرْانِ مَن يَخَافُ وَعِيدِ
(And you are not the one to force them. But warn by the Qur'an; him who fears My threat). Qatadah used to invoke Allah by saying,
"O Allah! Make us among those who fear Your threat and hope for Your promise, O Barr (Subtle, Kind, Courteous, and Generous), O Rahim (the Most Merciful."
This is the end of the Tafsir of Surah Qaf. All praise is due to Allah, He is for us, the most excellent Trustee