What is the ruling on saying, "Truly, there is no god but Allah" upon finishing the 'iqamah for prayer?

Saying "Truly, there is no god but Allah" upon the completion of the iqamah (call to commence prayer) has no evidence from the Sunnah, and the correct approach is to omit it. Dr. Bakr Abu Zayd mentioned in Mu'jam al-Manahi al-Lafziyyah that he did not find any basis for adding the word "truly." Sheikh Abdul Aziz bin Baz stated that saying "There is no god but Allah" is sufficient, and there is no need to add "truly," citing the Prophet's (peace be upon him) saying: "When you hear the mu'adhdhin (caller to prayer), say as he says." Thus, what is prescribed for the listener is to say what the mu'adhdhin says, then send blessings upon the Prophet (peace be upon him), then recite the Du'a al-Wasilah. As for the addition of the word "truly," it is better to omit it. The concern with persistently using this phrase is that it might fall under the category of an additive bid'ah (innovation).