Anas Radiyallahu 'Anhu reports:
"Rasulullah Sallallahu 'Alayhi Wasallam was sitting at the grave of his daughter (Sayyiditina Ummi Kulthum Radiyallahu 'Anha) and tears were flowing from his eyes. Sayyidina Rasulullah Sallallahu 'Alayhi Wasallam said: 'That person should enter the grave who did not have sexual relations that (previous) night'. Abu Talhah Radiyallahu 'Anhu replied: 'I did not'. At the request of Rasulullah Sallallahu 'Alayhi Wasallam he entered her grave"
English reference: Book 44, Hadith 310
Arabic reference: Book 45, Hadith 327