The Prophet (p.b.u.h) remained silent (for a while) and then said, "It is obligatory for every Muslim that he should take a bath once in seven days, when he should wash his head and body."
Hadith Referenceصحيح البخاري / كتاب الجمعة / 897
Hadith Gradingمحدثین:أحاديث صحيح البخاريّ كلّها صحيحة