Ibrahim, the son of the Prophet ﷺ, died when he was eighteen months old. The Messenger of Allah ﷺ did not pray over him. (Using translation from Abū Dāʾūd 3187)
لَقَدْ تُوُفِّيَ إِبْرَاهِيمُ ابْنُ رَسُولِ اللهِ وَهُوَ ابْنُ ثَمَانِيَةَ عَشَرَ شَهْرًا فَلَمْ يُصَلِّ عَلَيْهِ