Their evidence is to be found in the saheeh ahaadeeth of the Prophet (peace and blessings of Allaah be upon him), which prove that it is prescribed, for example:
‘उनी र म एउटै कक्षामा पढ्थ्यौँ, त्यसै क्रममा हाम्रो भेट भएको हो,’ उनले भने।