You will find many innovations amongst them. Rather, their daʿwah (call) is built upon innovations.
So as for Jamāʿat al-Tablīgh, then in front of you is what the noble brother, Muḥammad Ibn ʿAbd al-Wahhāb al-Waṣṣābī – may Allāh preserve him – has written. So he said,
: They act upon weak aḥādīth. Rather, they act upon fabricated aḥādīthand those that have no basis.
: You will find many innovations amongst them. Rather, their daʿwah (call) is built upon innovations. The backbone of their call is khurūj (going out) with a limit of three days in a week, four months in a year, and four months (at least) in a lifetime. And they have two excursions (jawlah) every week: one to the mosque that is prayed in, and the other is a roaming excursion. And they have two study circles every day: a circle in the mosque that is prayed in, and one circle at a house. So they will not be pleased with a person until he adheres to this. There is no doubt that this is an innovation in the Religion for which Allāh has sent down no authority.
: They feel that the call to Tawḥīd causes conflict for the Ummah.
: They feel that the call to the Sunnah causes conflict for the Ummah.
: Their leader says sternly, ‘An innovation that gathers the people together is better than a Sunnah which divides the people.’
: They have enmity towards Ahl al-Sunnah.
: They indirectly and directly deprive the people of beneficial knowledge.
: They feel that there is no salvation for the people, except through their path, and they strike a parable stating that this (their call) is like the Ark of Nūḥ; whosoever boards it is saved and whosoever does not, is destroyed. And they say, ‘Our daʿwah is like the Ark of Nūḥ.’ Indeed, I have heard the likes of this from them in Jordan and Yemen.
: They do not give importance to Tawḥīd al-Ulūhiyyah (Oneness of Allāh in Divinity) and Tawḥīd al-Asmāʾ wa-al-Ṣifāt (Oneness of Allāh in His Names and Attributes).
: Verily they do not prepare for seeking knowledge. They feel that the time spent in search of knowledge is a waste. And they possess other than what has been mentioned.
 Taken from Tarjumah Abī ’Abdur-Raḥmān Muqbil Ibn Hādī al-Wādiʿī (p. 137-138) of Shaykh Muqbil. Translated by Maaz Qureshi