إِلَّا تَنصُرُوهُ فَقَدْ نَصَرَهُ اللَّهُ إِذْ أَخْرَجَهُ الَّذِينَ كَفَرُوا ثَانِيَ اثْنَيْنِ إِذْ هُمَا فِي الْغَارِ إِذْ يَقُولُ لِصَاحِبِهِ لَا تَحْزَنْ إِنَّ اللَّهَ مَعَنَا ۖ فَأَنزَلَ اللَّهُ سَكِينَتَهُ عَلَيْهِ وَأَيَّدَهُ بِجُنُودٍ لَّمْ تَرَوْهَا وَجَعَلَ كَلِمَةَ الَّذِينَ كَفَرُوا السُّفْلَىٰ ۗ وَكَلِمَةُ اللَّهِ هِيَ الْعُلْيَا ۗ وَاللَّهُ عَزِيزٌ حَكِيمٌ (40)
(9:40) If you do not help your Prophet, (it does not matter): Allah did help him before when the disbelievers forced him to go away from his home, and he was but the second of two: when the two were in the cave; when he was saying to his Companion, "Be not distressed: indeed Allah is with us. " *42 Then Allah sent down peace of mind to him from Himself, and helped him with the forces you did not see, and made the word of the disbelievers abased. And Allah's Word is always supreme, for Allah is All-Mighty, All-Wise.
*42) This refers to the occasion when the disbelievers had decided to assassinate the Holy Prophet, and the very night fixed for his assassination he had left Makkah for Al-Madinah. By that time most of the Muslims had migrated to Al-Madinah in twos and threes and only a few helpless ones had remained behind in Makkah. As he was sure that he would be pursued, he took only Hadrat Abu Bakr with him and went southward instead of following the northern route to Al-Madinah and remained hidden in the Thaur Cave for three days. In the meantime the blood thirsty enemies had begun to make a thorough search for him all around Makkah and some of them reached the very mouth of the Cave where he was hidden. On this critical occasion Hadrat Abu Bakr naturally felt alarmed lest they should peep into the Cave, and see them. But the Holy Prophet remained as calm as before and reassured his Companion, saying, "Be not distressed: indeed Allah is with us."