1. Spitting: Islam has made it undesirable to spit in the mosque. Bukhari and Muslim reported on the authority of Anas ibn Malik that the Messenger of Allah (saw) said, “Spitting in the mosque is a sin and its indemnity is to bury it.” Some Schools of Thought have actually made it forbidden.

2. Trading and announcing the lost riding beast: Islam has made makruh to buy and sell in the mosques. Al-Tirmidhi and al-Nisai reported on the authority of Abu Hurayrah that the Messenger of Allah (saw) said, “If you saw a man buying and selling in the mosque, say to him, ‘May Allah never make you trade profitable’, and if you saw a man announcing the lost of his riding beast say to him, ‘May Allah never return it to you’.” Some Schools of Thoughts have actually made this forbidden.

3. Sitting in circles before the Friday prayer: Islam has made it forbidden to sit in circles before the Friday prayer, and some the Schools of Thoughts have in fact made it mubah..

4. The decorating and the boasting about in the mosques: Anas reported that the Messenger of Allah (saw) said, “The hour will not come until people boast in mosque.” This hadith has been reported by Bukhari, Muslim, al-Nisa‘i, Ibn Majah and Abu Dawud. Ibn ‘Abbas narrated that the Messenger of Allah (saw) said, “I was not ordered to decorate the mosques.” This hadith has been reported by Abu Dawud. This actually refers to the decorating and beautification of the mosques and some Schools of Thoughts have actually made it mubah.

5. The joining (crossing) of the fingers together in the mosques: the learned scholars of all Schools of Thought have consented on the undesirability of joining the fingers together in the mosque. Abu Sa‘id al-Khudri reported, “I entered the mosque with the Messenger of Allah (saw) and there was a man sitting in the middle of the mosque with his knees together and joining his fingers together.