AbuZumayl said: I asked Ibn Abbas, saying: What is that I find in my breast? He asked: What is it? I replied: I swear by Allah, I cannot speak about it. He asked me: Is it something doubtful? and he laughed. He then said: No one could escape that, until Allah, the exalted, revealed: "If thou went in doubt as to what we have revealed unto thee, and ask those who have been reading the Book from before thee." He said: If you find something in your heart, say: He is the first and the Last, the Evident and the Immanent, and He has full knowledge of all things.  

مَا هُوَ قُلْتُ وَاللَّهِ مَا أَتَكَلَّمُ بِهِ قَالَ فَقَالَ لِي أَشَىْءٌ مِنْ شَكٍّ قَالَ وَضَحِكَ قَالَ مَا نَجَا مِنْ ذَلِكَ أَحَدٌ قَالَ حَتَّى أَنْزَلَ اللَّهُ ﷻ { فَإِنْ كُنْتَ فِي شَكٍّ مِمَّا أَنْزَلْنَا إِلَيْكَ فَاسْأَلِ الَّذِينَ يَقْرَءُونَ الْكِتَابَ مِنْ قَبْلِكَ } الآيَةَ قَالَ فَقَالَ لِي إِذَا وَجَدْتَ فِي نَفْسِكَ شَيْئًا فَقُلْ { هُوَ الأَوَّلُ وَالآخِرُ وَالظَّاهِرُ وَالْبَاطِنُ وَهُوَ بِكُلِّ شَىْءٍ عَلِيمٌ }