Ibn ‘Umar said :
The prophet ﷺ passed by Ibn Sa’Id along with some of his companions. ‘Umar b. al-Kattab was among them. He was playing with boys near the fortress of Banu Maghalah. He was near the age of puberty (i.e. a boy). Before he was aware, the Messenger of Allah ﷺ gave him a pat on the back and said : Do you testify that you are the Messenger of Allah Ibn Sayyad then looked at him and said: I testify that you are the Apostle of Gentiles. Ibn Sayyad then said the prophet ﷺ then asked him : What comes to you ? He replied: One who speaks the truth and one who lies come to me. The prophet (may peace upon him) said: You are confused. The Messenger of Allah (may peace upon him) said to him: I have concealed something (in my hand) and he concealed the verse “the day when the sky will bring forth smoke (dukhan) clearly visible Ibn Sayyad said: It is smoke (dukhan) .The Messenger of Allah ﷺ said: Away with you, You cannot get farther than your rank. ‘Umar said: “Messenger of Allah, permit me to cut off his head. The Messenger of Allah ﷺ said: If he is the one (the Dajjal), you will not be given power over him, and if he is not, you will not do well in killing him.

حَدَّثَنَا أَبُو عَاصِمٍ، خُشَيْشُ بْنُ أَصْرَمَ حَدَّثَنَا عَبْدُ الرَّزَّاقِ، أَخْبَرَنَا مَعْمَرٌ، عَنِ الزُّهْرِيِّ، عَنْ سَالِمٍ، عَنِ ابْنِ عُمَرَ، أَنَّ النَّبِيَّ ﷺ مَرَّ بِابْنِ صَائِدٍ فِي نَفَرٍ مِنْ أَصْحَابِهِ فِيهِمْ عُمَرُ بْنُ الْخَطَّابِ وَهُوَ يَلْعَبُ مَعَ الْغِلْمَانِ عِنْدَ أُطُمِ بَنِي مَغَالَةَ وَهُوَ غُلاَمٌ فَلَمْ يَشْعُرْ حَتَّى ضَرَبَ رَسُولُ اللَّهِ ﷺ ظَهْرَهُ بِيَدِهِ ثُمَّ قَالَ " أَتَشْهَدُ أَنِّي رَسُولُ اللَّهِ " . قَالَ فَنَظَرَ إِلَيْهِ ابْنُ صَيَّادٍ فَقَالَ أَشْهَدُ أَنَّكَ رَسُولُ الأُمِّيِّينَ . ثُمَّ قَالَ ابْنُ صَيَّادٍ لِلنَّبِيِّ ﷺ أَتَشْهَدُ أَنِّي رَسُولُ اللَّهِ فَقَالَ لَهُ النَّبِيُّ ﷺ " آمَنْتُ بِاللَّهِ وَرُسُلِهِ " . ثُمَّ قَالَ لَهُ النَّبِيُّ ﷺ " مَا يَأْتِيكَ " . قَالَ يَأْتِينِي صَادِقٌ وَكَاذِبٌ . فَقَالَ لَهُ النَّبِيُّ ﷺ " خُلِّطَ عَلَيْكَ الأَمْرُ " . ثُمَّ قَالَ رَسُولُ اللَّهِ ﷺ " إِنِّي قَدْ خَبَّأْتُ لَكَ خَبِيئَةً " . وَخَبَّأَ لَهُ { يَوْمَ تَأْتِي السَّمَاءُ بِدُخَانٍ مُبِينٍ } قَالَ ابْنُ صَيَّادٍ هُوَ الدُّخُّ . فَقَالَ رَسُولُ اللَّهِ ﷺ " اخْسَأْ فَلَنْ تَعْدُوَ قَدْرَكَ " . فَقَالَ عُمَرُ يَا رَسُولَ اللَّهِ ائْذَنْ لِي فَأَضْرِبَ عُنُقَهُ . فَقَالَ رَسُولُ اللَّهِ ﷺ " إِنْ يَكُنْ فَلَنْ تُسَلَّطَ عَلَيْهِ " . يَعْنِي الدَّجَّالَ " وَإِلاَّ يَكُنْ هُوَ فَلاَ خَيْرَ فِي قَتْلِهِ " .