Sahih Al Bukhari – Book of To Make The Heart Tender (Ar-Riqaq)
Volumn 008, Book 076, Hadith Number 486.
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Narated By Abu Huraira : The Prophet said Allah will give shade to seven (types of people) under His Shade (on the Day of Resurrection). (one of them will be) a person who remembers Allah and his eyes are then flooded with tears.