Interrupting Thikr after prayer to return greeting of Salaam
3-1-2018 | IslamWeb
Question:
Assalaamu alaykum wa rahmatullaahi wa barakaatuhu. Dear Shaykh, I have a question regarding the prescribed Thikr (expressions of remembrance of Allah) after the prayer. I read a fatwa that said that it should be done before talking to anyone. So my question is: what if someone says 'Assalaamu alaykum' to me while I am doing this Thikr, should I ignore them and keep doing the Thikr, or should I respond to it even though I did not finish the prescribed Thikr after the prayer? May Allah reward you. Wassalaam.
Answer:
All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad 
is His slave and Messenger.
If someone greets you with the greeting of Salaam while you are reciting the prescribed Thikr after prayer, it is recommended that you interrupt the Thikr to return the Salaam and then resume the recitation of the Thikr.
An-Nawawi 
wrote, "Chapter on the occasions in which it is recommended to stop reciting Thikr and resume it afterward, including the following: when the person reciting Thikr is greeted with the Salaam, he responds to the greeting and then resumes his Thikr." [Al-Athkaar]
Some Shaafiʻi scholars gave preference to the view that interrupting Thikr, such as Tasbeeh (saying: Subhaan Allah [glory to Allah]) after prayer, even by engaging in brief talks, is considered ending the recitation abruptly before completing the Thikr. However, they excluded the situation when such talk is classified as Thikr as well such as returning the greetings or the like. Haashiyat Al-Jamal ʻala Al-Manhaj reads:
"Ending the fast and prayer abruptly before completing them is clear given their nature. As for reciting Soorah Al-Kahf, Tasbeeh, and the like, does ending the recitation abruptly mean turning away from it and engaging in other activity without completing it, or does it also mean interrupting it with talk, even if brief, and then resuming the recitation? Scholars held different opinions in this regard. The second is the most likely correct view, unless that interrupting talk is required, such as returning the greeting of Salaam or repeating the words of the Athaan."
Allah knows best.