(Imām Bukhārī narrates): Al-Salt ibn Muhammad narrated to us, he said: Mahdī narrated to us, from Wāsil, from Abī Wā'il, from Hudhaifah, he narrates that:
he saw a man who was not completing rukū' and sujūd in prayer. When he finished praying, Hudhaifah, may Allāh be pleased with him, said to him: You have not prayed a (complete) prayer, and if you were to die (praying in this way), you would die contrary to the sunnah of the Prophet ﷺ.
Reference: Sahih Al Bukhari 808