"When the Prophet ﷺ commanded them to dig the trench (Al-Khandaq), there was a rock in their way preventing them from digging. The Messenger of Allah ﷺ stood, picked up a pickaxe, put his Rida' (upper garment) at the edge of the ditch and said: 'And the Word of your Lord has been fulfilled in truth and in justice. None can change His Words. And He is the All-Hearer, the All-Knower.' [1] One-third of the rock broke off while Salman Al-Farisi was standing there watching, and there was a flash of light when the Messenger of Allah ﷺstruck (the rock). Then he struck it again and said: 'And the Word of your Lord has been fulfilled in truth and in justice. Nonce can change His Words. Ans He is the All-Hearer, the All-Knower' And another third of the rock broke off and there was another flash of light, which Salman saw. Then he struck (the rock) a third time and said: 'And the Word of your Lord has been fulfilled in truth and in justice. None can change His Words. And He is the All-Hearer, the All-Knower.' The last third fell, and the Messenger of Allah ﷺ came out, picked up his Rida' and sat down. Salman said: 'O Messenger of Allah, Each time you struck the rock there was a flash of light.' The Messenger of Allah ﷺ said to him: 'O Salman, did you see that?' He said: 'Yes, by the One Who sent you with the truth, O Messenger of Allah.' He said: 'When I struck the first blow, the cities of Kisra and their environs were shown to me, and many other cities, and I saw them with my own eyes.' Those of his Companions who were present said: 'O Messenger of Allah, pray to Allah to grant us victory and to give us their land as spoils of war, and to destroy their lands at our hands.' So the Messenger of Allah ﷺ prayed for that. (Then he said:) 'Then I struck the second blow and the cities of Caesar and their environs were shown to me, and I saw them with my own eyes.' They said: 'O Messenger of Allah, pray to Allah to grant us victory and to give us their lands as spoils of war, and to destroy their lands at our hands.' So the Messenger of Allah ﷺ prayed for that. (Then he said:) 'Then I struck the third blow and the cities of Ethiopia were shown to me, and the villages around them, and I saw them with my own eyes.' But the Messenger of Allah ﷺ said at that point: 'Leave the Ethiopians alone so long as they leave you alone, and leave the Turks alone so long as they leave you alone.'" [1] An-An'am 6:115. (Using translation from Nasāʾī 3176)  

عَنْ رَجُلٍ مِنْ أَصْحَابِ النَّبِيِّ ﷺ قَالَ لَمَّا أَمَرَ النَّبِيُّ ﷺ بِحَفْرِ الْخَنْدَقِ عَرَضَتْ لَهُمْ صَخْرَةٌ حَالَتْ بَيْنَهُمْ وَبَيْنَ الْحَفْرِ فَقَامَ النَّبِيُّ ﷺ وَأَخَذَ الْمِعْوَلَ وَوَضَعَ رِدَاءَهُ نَاحِيَةَ الْخَنْدَقِ وَضَرَبَ وَقَالَ {وَتَمَّتْ كَلِمَةُ رَبِّكَ صِدْقًا وَعَدْلًا لَا مُبَدِّلَ لِكَلِمَاتِهِ وَهُوَ السَّمِيعُ الْعَلِيمُ} فَنَدَرَ ثُلُثُ الْحَجَرِ وَسَلْمَانُ الْفَارِسِيُّ قَائِمٌ يَنْظُرُ فَبَرَقَ مَعَ ضَرْبَةِ رَسُولِ اللهِ ﷺ بَرْقَةٌ ثُمَّ ضَرَبَ الثَّانِيَةَ وَقَالَ {وَتَمَّتْ كَلِمَةُ رَبِّكَ صِدْقًا وَعَدْلًا لَا مُبَدِّلَ لِكَلِمَاتِهِ وَهُوَ السَّمِيعُ الْعَلِيمُ} فَنَدَرَ الثُّلُثُ الْآخَرُ فَبَرَقَتْ بَرْقَةٌ يَرَاهَا سَلْمَانُ ثُمَّ ضَرَبَ الثَّالِثَةَ وَقَالَ {وَتَمَّتْ كَلِمَةُ رَبِّكَ صِدْقًا وَعَدْلًا لَا مُبَدِّلَ لِكَلِمَاتِهِ وَهُوَ السَّمِيعُ الْعَلِيمُ} فَنَدَرَ الثُّلُثُ الْبَاقِي وَبَرَقَ بَرْقَةٌ وَخَرَجَ رَسُولُ اللهِ ﷺ وَأَخَذَ رِدَاءَهُ وَجَلَسَ قَالَ سَلْمَانُ يَا رَسُولَ اللهِ رَأَيْتُكَ حِينَ ضَرَبْتَ لَا تَضْرِبُ ضَرْبَةً إِلَّا كَانَتْ مَعَهَا بَرْقَةٌ قَالَ لَهُ رَسُولُ اللهِ ﷺ «يَا سَلْمَانُ رَأَيْتَ ذَلِكَ؟» قَالَ إِي وَالَّذِي بَعَثَكَ بِالْحَقِّ يَا رَسُولَ اللهِ قَالَ فَإِنِّي حِينَ ضَرَبْتُ الضَّرْبَةَ الْأُولَى رُفِعَتْ لِي مَدَائِنُ كِسْرَى وَمَا حَوْلَهَا وَمَدَائِنُ كَثِيرَةٌ حَتَّى رَأَيْتُهَا بِعَيْنَيَّ فَقَالَ لَهُ مَنْ حَضَرَهُ مِنْ أَصْحَابِهِ يَا رَسُولَ اللهِ ادْعُ اللهَ أَنْ يَفْتَحَهَا عَلَيْنَا وَيُغَنِّمَنَا ذَرَارِيَّهُمْ وَيُخَرِّبَ بِأَيْدِينَا بِلَادَهُمْ قَالَ فَدَعَا رَسُولُ اللهِ ﷺ بِذَلِكَ قَالَ ثُمَّ ضَرَبْتُ الضَّرْبَةَ الثَّانِيَةَ فَرُفِعَتْ لِي مَدَائِنُ قَيْصَرَ وَمَا حَوْلَهَا حَتَّى رَأَيْتُهَا بِعَيْنَيَّ قَالَ يَا رَسُولَ اللهِ ادْعُ اللهَ يَفْتَحُهَا عَلَيْنَا وَيُغَنِّمَنَا ذَرَارِيَّهُمْ وَيُخَرِّبُ بِأَيْدِينَا بِلَادَهُمْ فَدَعَا رَسُولُ اللهِ ﷺ ثُمَّ ضَرَبْتُ الثَّالِثَةَ فَرُفِعَتْ لِي مَدَائِنُ الْحَبَشَةِ وَمَا حَوْلَهَا مِنَ الْقُرَى حَتَّى رَأَيْتُهَا بِعَيْنَيَّ فَقَالَ رَسُولُ اللهِ ﷺ عِنْدَ ذَلِكَ «دَعُوا الْحَبَشَةَ مَا وَدَعُوكُمْ وَاتْرُكُوا التُّرْكَ مَا تَرَكُوكُمْ»  

The last hour will not come before the Muslims fight with the Turks, a people whose faces look as if they were shields covered with skin, and who will wear sandals of hair. (Using translation from Abū Dāʾūd 4303)  

أَنَّ رَسُولَ اللهِ ﷺ قَالَ «لَا تَقُومُ السَّاعَةُ حَتَّى يُقَاتِلَ الْمُسْلِمُونَ التُّرْكَ قَوْمٌ وُجُوهُهُمْ كَالْمَجَانِّ الْمُطْرَقَةِ يَلْبَسُونَ الشَّعْرَ وَيَمْشُونَ فِي الشَّعْرِ»