The prohibition of sadl and of a man covering his mouth in prayer

It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) forbade letting the garment hang down (in the prayer) and a man covering his mouth.
This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record the mention of covering the mouth in the prayer.

Sayyiduna Jabir bin Abdullah (may Allah be pleased with him) narrates: I was with the Messenger of Allah (peace and blessings be upon him) on a military expedition. He (peace and blessings be upon him) stood up to pray. I had only a single cloak on me; I tried to cross its two ends over my shoulders in opposite directions and held it firmly so that it would not fall. Then I stood on the left side of the Messenger of Allah (peace and blessings be upon him). He (peace and blessings be upon him) took me by the hand, turned me around and made me stand on his right side. Then Ibn Sakhr came and stood on his left side, and he (peace and blessings be upon him) took both of us by the hand and made us stand behind him. Jabir said: the Messenger of Allah (peace and blessings be upon him) was watching me and I was not aware of it; then I realised, and he (peace and blessings be upon him) signalled to me to tie the cloak around me as a waist-wrapper. When he (peace and blessings be upon him) finished the prayer, he said: "O Jabir!" I said: Labbayk, O Messenger of Allah! He (peace and blessings be upon him) said: "If the garment is wide, cross its ends (over the shoulders) in opposite directions, and if it is narrow, tie it around your waist."
This hadith is sahih (authentic) on the condition of Muslim, but the two Shaykhs did not record it.