Hadithcore
Al-Adab Al-Mufrad, 939
sahih· Al-Albani

Abu Hurayra said, "Wish mercy on a person once, twice and three times. Anything more than that is a cold."

حَدَّثَنَا قُتَيْبَةُ، قَالَ‏:‏ حَدَّثَنَا سُفْيَانُ، عَنِ ابْنِ عَجْلاَنَ، عَنِ الْمَقْبُرِيِّ، عَنْ أَبِي هُرَيْرَةَ قَالَ‏:‏ شَمِّتْهُ وَاحِدَةً وَثِنْتَيْنِ وَثَلاَثًا، فَمَا كَانَ بَعْدَ هَذَا فَهُوَ زُكَامٌ‏.‏

References2 variants
In-Book Reference
Book 40, Hadith 21
English Reference
Book 40, Hadith 939