قال الشافعي ) وقول آمين يدل على أن لا بأس أن يسأل العبد ربه في الصلاة كلها في الدين والدنيا مع ما يدل من السنن على ذلك ( قال الشافعي ) ولو قال مع : آمين رب العالمين وغير ذلك من ذكر الله كان حسنا لا يقطع الصلاة شيء من ذكر الله
❝If one was to add "Yaa Rabbal 'alamīn" after "amīn" (after surat al fatiha) then that is good because salah is NEVER nullified by a dhikr of Allāh ❞
— Imām Al-Shafiee in Al-Umm (2/250)
That was the giant Imam Ash Shafiee رحمه الله for you. By today's modern standards of tabdee', many overzealous folks would consider this is an innovation.
- Via Ahmed Faizan Alam
This also validates that we can also say "Aameen" With the addition of "Ya Rabbul Aalameen" after the dua.
