Abu Dawud

Benefits and Issues:
Question: What is the ruling on responding to "Qad qamatis salah"?
During the iqamah, when «قد قامت الصلاة» is said, some people respond by saying «اقامها الله و ادامها». This is not permissible, because saying so is not established from the Messenger of Allah (sallallahu alayhi wa sallam). The hadith that has been narrated regarding this is extremely "weak" and not suitable for practice or as evidence. See:

It is narrated in SA that when Sayyiduna Bilal (radi Allahu anhu) began to say the iqamah, and when he said «قد قامت الصلاة», the Noble Prophet (sallallahu alayhi wa sallam) responded by saying «اقامها الله و ادامها». [سنن ابي داود : 528، عمل اليوم واليله لا بن السني : 105] EA SH Commentary: EH

This narration is "weak" for two reasons:
➊ Its narrator, Muhammad bin Thabit Abdi, is considered "weak" by the majority of the hadith scholars, as:

◈ Hafiz Nawawi (rahimahullah) writes:
«وليس هو بالقوي عند اكثر المحدثين»
"According to most of the hadith scholars, he is not a reliable narrator." [خلاصه الاحكام :217/1 ح : 559، نصب الرايه للزيلعي : 5/1، 6]

➋ «رجل من اهل الشام» is unknown and "ambiguous."

The religion is based on authentic narrations reported by trustworthy narrators. Furthermore, this issue pertains to legal rulings (ahkam shar‘iyyah), not to virtues (fada’il).

528. Commentary:
This narration is weak in its chain of transmission; however, it is deduced from the ahadith of the previous chapter that the iqamah should also be responded to, and in response to «قد قامت الصلوة», the same words should be repeated. For details, see: [فتح الباري : 92/2]