Pronouncing it is not a condition but is recommended; due to the presence of intention; because of the differences in time and the many distractions on the hearts after the time of the followers. See: Hidayah Ibn Al-Imad p. 456, Al-Durr Al-Mukhtar 1: 415, Naf' Al-Mufti p. 237, and Al-Maraqi p. 217.