Hadith regarding the saying of “Allahumma Rabbana laka-l-hamd or Rabbana walaka-l hamd” while in salah
Narrated by Abu Huraira: Allah’s Apostle said, “When the Imam says, “Sami’ a-l-lahu Liman hamida,” you should say, “Allahumma Rabbana laka-l-hamd.” And if the saying of any one of you…