"The truth is from your Lord, so do not be among the doubters," meaning: the skeptics that you are the Messenger of Allah, and they recognize Islam.
﴿الْحَقُّ مِنْ رَبِّكَ فَلا تَكُونَنَّ من الممترين﴾ يَعْنِي: الشاكين؛ أَنَّك رَسُول اللَّهِ، ويعرفون الْإِسْلَام
