Abu Sa`id and Abu Hurairah (May Allah be pleased with him) reported that the Prophet (peace and blessings of Allah be upon him) said: "Never a believer is stricken with a discomfort, an illness, an anxiety, a grief or mental worry or even the pricking of a thorn but Allah will expiate his sins on account of his patience". [Al-Bukhari and Muslim]
Commentary: This Hadith mentions the special Grace and Mercy of Allah for the Muslims. It relates how Allah turns the hardships and troubles suffered by a Muslim into a means of expiation for his sins. But this is only possible if the believer exercises patience. However, if he starts wailing instead of showing patience then beside suffering hardships, he would be deprived of the reward which lies in bearing them patiently. Thus, he shall have to take the burden of additional sins also.