عن الفتوى
Ruling on saying “Ya Rahmat Allaah (O Mercy of Allaah)”
What is the ruling on what some people say, “Ya Rahmat Allaah (O Mercy of Allaah)”?
الإجابة:
Praise be to Allaah.
This is not permitted, this is like calling upon one of the attributes of Allaah).
From Fataawa Samaahat al-Shakh Muhammad ibn Ibraaheem (may Allaah have mercy on him) 1/117