إِذَا مَرَّتِ الْجَمَاعَةُ بِقَوْمٍ أَجْزَأَهُمْ أَنْ يُسَلِّمَ وَاحِدٌ مِنْهُمْ وَ إِذَا سَلَّمَ عَلَى الْقَوْمِ وَ هُمْ جَمَاعَةٌ أَجْزَأَهُمْ أَنْ يَرُدَّ وَاحِدٌ مِنْهُمْ.
“If one person from a group passing by another group offers the greeting of peace it is sufficient for all and so also is for an answer if only one person from the stationary group responds.”