Sunan Abi Dawud 4400
A similar tradition has also been transmitted by al-A’mash through a different chain of narrators. He also said :
“... . Till he reaches puberty , and a lunatic till he is restored to consciousness.”   ‘Umar then began to utter: Allah is most great.
حَدَّثَنَا يُوسُفُ بْنُ مُوسَى، حَدَّثَنَا وَكِيعٌ، عَنِ الأَعْمَشِ، نَحْوَهُ وَقَالَ أَيْضًا حَتَّى يَعْقِلَ ‏.‏ وَقَالَ وَعَنِ الْمَجْنُونِ حَتَّى يُفِيقَ ‏.‏ قَالَ فَجَعَلَ عُمَرُ يُكَبِّرُ ‏.‏