«إذا عطس أحدكم فليشمته جليسه فإن زاد على ثلاث فهو مزكوم ولا يشمت بعد ثلاث»
The Prophet (peace and blessings be upon him) said:
"When one of you sneezes, let the person sitting with him respond to him. If he sneezes more than three times, he has a cold, so he is not to be responded to after three times."
Hadith Referenceصحیح الجامع الصغیر / حرف الألف / 684