Messenger of Allah ﷺ said, "If anyone of you can get one rakʿa of the ʿAsr prayer before sunset, he should complete his prayer. If any of you can get one rakʿa of the Fajr prayer before sunrise, he should complete his prayer."  

قَالَ رَسُولُ اللَّهِ ﷺ إِذَا أَدْرَكَ أَحَدُكُمْ سَجْدَةً مِنْ صَلاَةِ الْعَصْرِ قَبْلَ أَنْ تَغْرُبَ الشَّمْسُ فَلْيُتِمَّ صَلاَتَهُ وَإِذَا أَدْرَكَ سَجْدَةً مِنْ صَلاَةِ الصُّبْحِ قَبْلَ أَنْ تَطْلُعَ الشَّمْسُ فَلْيُتِمَّ صَلاَتَهُ  

My father said, "I heard Messenger of Allah ﷺ saying, 'The period of your stay as compared to the previous nations is like the period equal to the time between the ʿAsr prayer and sunset. The people of the Torah were given the Torah and they acted (upon it) till midday then they were exhausted and were given one Qirat (of gold) each. And then the people of the Gospel were given the Gospel and they acted (upon it) till the ʿAsr prayer then they were exhausted and were! given one Qirat each. And then we were given the Qur'an and we acted (upon it) till sunset and we were given two Qirats each. On that the people of both the scriptures said, 'O our Lord! You have given them two Qirats and given us one Qirat, though we have worked more than they.' Allah said, 'Have I usurped some of your right?' They said, 'No.' Allah said: "That is my blessing I bestow upon whomsoever I wish."  

أَنَّهُ أَخْبَرَهُ أَنَّهُ سَمِعَ رَسُولَ اللَّهِ ﷺ يَقُولُ إِنَّمَا بَقَاؤُكُمْ فِيمَا سَلَفَ قَبْلَكُمْ مِنَ الأُمَمِ كَمَا بَيْنَ صَلاَةِ الْعَصْرِ إِلَى غُرُوبِ الشَّمْسِ أُوتِيَ أَهْلُ التَّوْرَاةِ التَّوْرَاةَ فَعَمِلُوا حَتَّى إِذَا انْتَصَفَ النَّهَارُ عَجَزُوا فَأُعْطُوا قِيرَاطًا قِيرَاطًا ثُمَّ أُوتِيَ أَهْلُ الإِنْجِيلِ الإِنْجِيلَ فَعَمِلُوا إِلَى صَلاَةِ الْعَصْرِ ثُمَّ عَجَزُوا فَأُعْطُوا قِيرَاطًا قِيرَاطًا ثُمَّ أُوتِينَا الْقُرْآنَ فَعَمِلْنَا إِلَى غُرُوبِ الشَّمْسِ فَأُعْطِينَا قِيرَاطَيْنِ قِيرَاطَيْنِ فَقَالَ أَهْلُ الْكِتَابَيْنِ أَىْ رَبَّنَا أَعْطَيْتَ هَؤُلاَءِ قِيرَاطَيْنِ قِيرَاطَيْنِ وَأَعْطَيْتَنَا قِيرَاطًا قِيرَاطًا وَنَحْنُ كُنَّا أَكْثَرَ عَمَلاً قَالَ قَالَ اللَّهُ ﷻ هَلْ ظَلَمْتُكُمْ مِنْ أَجْرِكُمْ مِنْ شَىْءٍ قَالُوا لاَ قَالَ فَهْوَ فَضْلِي أُوتِيهِ مَنْ أَشَاءُ  

The Prophet ﷺ said, "The example of Muslims, Jews and Christians is like the example of a man who employed laborers to work for him from morning till night. They worked till midday and they said, 'We are not in need of your reward.' So the man employed another batch and said to them, 'Complete the rest of the day and yours will be the wages I had fixed (for the first batch). They worked until the time of the ʿAsr prayer and said, 'Whatever we have done is for you.' He employed another batch. They worked for the rest of the day till sunset, and they received the wages of the two former batches."  

عَنِ النَّبِيِّ ﷺ مَثَلُ الْمُسْلِمِينَ وَالْيَهُودِ وَالنَّصَارَى كَمَثَلِ رَجُلٍ اسْتَأْجَرَ قَوْمًا يَعْمَلُونَ لَهُ عَمَلاً إِلَى اللَّيْلِ فَعَمِلُوا إِلَى نِصْفِ النَّهَارِ فَقَالُوا لاَ حَاجَةَ لَنَا إِلَى أَجْرِكَ فَاسْتَأْجَرَ آخَرِينَ فَقَالَ أَكْمِلُوا بَقِيَّةَ يَوْمِكُمْ وَلَكُمُ الَّذِي شَرَطْتُ فَعَمِلُوا حَتَّى إِذَا كَانَ حِينَ صَلاَةِ الْعَصْرِ قَالُوا لَكَ مَا عَمِلْنَا فَاسْتَأْجَرَ قَوْمًا فَعَمِلُوا بَقِيَّةَ يَوْمِهِمْ حَتَّى غَابَتِ الشَّمْسُ وَاسْتَكْمَلُوا أَجْرَ الْفَرِيقَيْنِ