2 verses have
serious
in Edition Clear Qur'an by Talal Itani / Hud (Hud)

11:62They said, “O Saleh, we had hopes in you before this. Are you trying to prevent us from worshiping what our parents worship? We are in serious doubt regarding what you are calling us to.”

11:110We gave Moses the Scripture, but it was disputed. Were it not for a prior word from your Lord, it would have been settled between them. They are in serious doubt concerning it.