Allah tells His Prophet to say to these polytheists who worship others besides Allah,أَفَغَيْرَ اللّهِ أَبْتَغِي حَكَمًاShall I seek a judge other than Allah...between you and I,وَهُوَ الَّذِي أَنَزَلَ إِلَيْكُمُ الْكِتَابَ مُفَصَّلًwhile it is He Who has sent down unto you the Book, explained... (in detail),وَالَّذِينَ اتَيْنَاهُمُ الْكِتَابَand those unto whom We gave the Scripture,the Jews and the Christians,يَعْلَمُونَ أَنَّهُ مُنَزَّلٌ مِّن رَّبِّكَ بِالْحَقِّknow that it is revealed from your Lord in truth.because the previous Prophets have conveyed the good news of you coming to them.Allah's statement,فَلَ تَكُونَنَّ مِنَ الْمُمْتَرِينَSo be not you of those who doubt.is similar to His other statement,فَإِن كُنتَ فِي شَكٍّ مِّمَّأ أَنزَلْنَأ إِلَيْكَ فَاسْأَلِ الَّذِينَ يَقْرَءُونَ الْكِتَـبَ مِن قَبْلِكَ لَقَدْ جَأءَكَ الْحَقُّ مِن رَّبِّكَ فَلَ تَكُونَنَّ مِنَ الْمُمْتَرِينَSo if you are in doubt concerning that which We have revealed unto you, then ask those who are reading the Book before you. Verily, the truth has come to you from your Lord. So be not of those who doubt (it). (10:94)The conditional `if' in this Ayah does not mean that `doubt' will ever occur to the Prophet.Allah said