It is narrated from Hazrat Abu Rafi' (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) forbade a man from performing prayer while his hair is tied in a knot on his head.
Hadith Referenceمسند احمد / مسند الأنصار رضي الله عنهم / 23856
Hadith Gradingحکم دارالسلام:صحيح لغيره، وهذا إسناد اختلف فيه فى تعيين الرجل المبهم، ثم إنه اختلف فى إسناده على مخول