Assalamualaikum ustaz. Is it permissible for a person to combine the opinions from different madhhabs in a single act of worship? For instance, he combined it in prayer. Is it included as tatabbu’ al-rukhas? Hope for an explanation.
Waalaikumussalam wrt. wbt.,
Alhamdulillah, praise and gratitude to Allah SWT for His countless blessings for us all. Praise and salutations to our beloved Prophet Muhammad PBUH, his family, companions, and all those who follow his footsteps until the Final day.
Tatabbu’ al-Rukhas is an action adopted by a person who combines or chooses the easiest opinion from every madhhab on the issues that he’s facing.
In this matter, there is a difference of opinions among scholars as to whether it is permissible or otherwise:
First opinion: Imam Ghazali holds the opinion that Tatabbu’ al-Rukhas in madhhabs is prohibited for it is more to surrendering to humans’ desires (nafs). This is a strong opinion in madhhab Maliki and Hanbali. It is cited from Ibnu Abdil Bar and Ibnu Hazim, who said, it is impermissible for a muqallib (common person) to practise Tatabbu’ al-Rukhas through ijma’ , for it leads to the elimination of taklif in every khilaf matter. 
Second opinion: Imam Qarafi, most Syafie scholars and the strongest opinion in madhhab Hanafi stated that Tatabbu’ al-Rukhas is permissible, their reasoning is that there is no restriction from the shariah, for a person is permissible to choose an easy opinion when there is a way to take an easy opinion as long as he hasn’t taqlid with the opinion of another mujtahid in the same issue because a muqallid cannot retract from the opinion that he has practised. 
However, in this issue, Imam Qarafi set a condition that there wouldn’t be an ending when a person takes a rukhsah – that he’ll take an invalid opinion of scholar for his taqlid.
For example: He follows the opinion of Imam Malik in the case of an ablution isn’t invalidated when a man touches a woman without desire, at the same time he performs his ablution following the opinion of Imam Syafie which states that it is not obligatory to rub his ablution body parts during ablution or it is not obligatory to wipe or wash his whole head. Indeed, his prayer will be invalid because his ablution is invalid according to both these imams. 
Syeikh Dr Wahabh al-Zuhaili stated this condition is not based on any evidences and ijma’. When a person is permissible to choose between mujtahids and can choose (taqlid) the prioritized between the madhhabs, then it is permissible to take different opinions between mujtahids. 
In this issue, Syeikh Hasanain Makhluf, Syeikh Muti and Dr Ahmad Mansur are of the opinion talfiq or Tatabbu’ al-Rukhas is permissible.
In his book Fatawa Syar’iyyah wa Buhuth Islamiyyah (pg. 76), Syeikh Hasanain stated his opinion saying, talfiq is permissible in different issues whether in exigent or non-exigent situations which includes worship and muamalah for the blessing of the ummah. He further said that a person performing ablution using madhhab Hanafi and praying with the taqlid of madhhab Syafir or vice versa is permissible.
He stated tattabu’ rukhas (following the easier solution) in different issues is permissible for it doesn’t contradict the ijmak. He said so when replying to the question of a person who asked for a fatwa regarding talfiq using tattabu’ rukhas is permissible, for instance, when a person performs ablution using a little bit of musta’mal water then with taqlid to madhhab Hanafi which states that rubbing (wiping) and intention is not obligatory, hence all these actions are permissible.
He further stated that a person who performs ablution with madhhab Syafie then accidentally touched a woman and pray without reperforming his ablution using the taqlid of madhhab Hanafi, then this talfiq is permissible.
He explained that prohibited talfiq is when tattabu’ rukhas is done for one issue, for example, a person performs the ablution and leave the order following madhhab Hanafi and wash less than ¼ of his head, then this is prohibited. 
While Syeikh Dr Wahbah Zuhaili concluded the issue of talfiq saying, “There’s no issue of performing tattabu’ rukhas in an exigent situation or there is a necessity without any intention to have fun or belittle and on the condition that it doesn’t lead to prohibited talfiq.” 
The issue of combining several madhhabs in a single act of worship
In answering the above question, here we cite several matters that should be considered before performing any act of worship or taking another madhhab’s opinion in certain worship:
First: If the purpose is to Tatabbu’ al-Rukhas (تتبـع الرخص), then it should be avoided. Tatabbu’ al-Rukhas meant here is to take the easy route/opinion in a certain fiqh issue especially without the process of tarjih following the syarak and just following nafs. Al-Imam Ibn Abd al-Bar and al-Imam Ibn Hazm stated this act is prohibited through ijma’. al-Imam al-Ghazali, al-Imam al-Nawawi, al-Imam Ibn al-Qayyim and al-Imam al-Syatibi also hold the opinion that this tatabu’ al-Rukhas is prohibited.
Second: If there is a sahih hadith as well as sahih understanding regarding the hadith, then it can be practised. This is as supported by the statement of al-Imam al-Syafi’e Rahimahullah:
إذَا صَحَّ الْحَدِيثُ فَهُوَ مَذْهَبِي
“If a hadith is sahih, then that is my madhhab.” 
Third: Following one madhhab and learning about it in-depth, in our opinion is prioritized for uniformity and exiting khilaf of other people’s opinions which could cause rise to different perceptions, as long as the matter follows al-Quran and al-Sunnah.
 See Usul al-Fiqh al-Islami by Syeikh Dr Wahbah al-Zuhaili, 2/1182
 This ijma’ claim is inaccurate for there are those who ruled it permissible such as Kamal Ibnu Humam.
 See Usul al-Fiqh al-Islami, 2/1182
 See Fatawa Syar’iyyah wa Buhuth Islamiyyah by Syeikh Hasanain Makhluf pg. 76
 See Usul al-Fiqh al-Islami, 2/1182
 See Usul al-Fiqh al-Islami, 2/1183
 See Fatawa Syar’iyyah, pg. 77-78
 See al-Rukhas al-Syar’iyyah: Ahkamuha wa Dawabituha, pg. 18
 See al-Majmu’ Syarh al-Muhazzab, 15/461; Tuhfah al-Muhtaj, 1/54 and Mughni al-Muhtaj, 1/110