"When Malik bin Hubairah performed Salat for a funeral and the people were few he would divide them into three groups (rows) then say: 'The Messenger of Allah said: "For whomever three rows perform Salat, then it is granted."  

فَتَقَالَّ النَّاسَ عَلَيْهَا جَزَّأَهُمْ ثَلاَثَةَ أَجْزَاءٍ ثُمَّ قَالَ قَالَ رَسُولُ اللَّهِ ﷺ مَنْ صَلَّى عَلَيْهِ ثَلاَثَةُ صُفُوفٍ فَقَدْ أَوْجَبَ قَالَ وَفِي الْبَابِ عَنْ عَائِشَةَ وَأُمِّ حَبِيبَةَ وَأَبِي هُرَيْرَةَ وَمَيْمُونَةَ زَوْجِ النَّبِيِّ ﷺ  

The Prophet said: "No one among the Muslim dies, and Salat is performed for him by a community of Muslims reaching one hundred, and they intercede (supplicate) for him, except that their intercession for him is accepted." In his narration, 'Ali bin Hujr said: "One hundred or more than that."  

عَنِ النَّبِيِّ ﷺ قَالَ لاَ يَمُوتُ أَحَدٌ مِنَ الْمُسْلِمِينَ فَتُصَلِّي عَلَيْهِ أُمَّةٌ مِنَ الْمُسْلِمِينَ يَبْلُغُونَ أَنْ يَكُونُوا مِائَةً فَيَشْفَعُوا لَهُ إِلاَّ شُفِّعُوا فِيهِ وَقَالَ عَلِيُّ بْنُ حُجْرٍ فِي حَدِيثِهِ مِائَةً فَمَا فَوْقَهَا