Al-Mu'jam al-Awsat 8666 — from Shu'bah, the freed slave of Ibn Abbas

It is narrated from Shu'bah, the freed slave of Ibn Abbas (may Allah have mercy on him), or Kurayb, the freed slave of Ibn Abbas (may Allah have mercy on him), that Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) passed by Abdullah bin al-Harith bin Rabi'ah while he was praying, with the hair of his head braided and tied up from behind. Sayyiduna Ibn Abbas (may Allah be pleased with them both) stopped by him, did not move away, and began to undo the knot of his hair, and Abdullah bin al-Harith let him undo it until he had finished undoing it; then he sat down. When Ibn al-Harith finished the prayer, he came to him and said: "Why did you do what you just did with my head?" He said: I heard the Messenger of Allah (peace and blessings be upon him) say: "The example of one who prays with the hair of his head tied up from behind is like one who prays wrapped up (with hands and feet bound)."
Imam al-Tabarani (may Allah have mercy on him) said: "No one narrated this hadith from Amr bin al-Harith except Layth bin Sa'd."