Sahih Bukhari Volume 002, Book 023, Hadith Number 391.
Narated By 'Abdullah bin 'UmarÂ : Sad bin 'Ubada became sick and the Prophet along with 'Abdur Rahman bin 'Auf, Sad bin Abi Waqqas and 'Abdullah bin Masud visited him to enquire about his health. When he came to him, he found him surrounded by his household and he asked, "Has he died?" They said, "No, O Allah's Apostle." The Prophet wept and when the people saw the weeping of Allah's Apostle (p.b.u.h) they all wept. He said, "Will you listen? Allah does not punish for shedding tears, nor for the grief of the heart but he punishes or bestows His Mercy because of this." He pointed to his tongue and added, "The deceased is punished for the wailing of his relatives over him." 'Umar used to beat with a stick and throw stones and put dust over the faces (of those who used to wail over the dead).