Hawzah News Agency (Birmingham, UK) - The 16-year-old was inside the Jamiat-ul-Muslimin Mosque in Tennyson Road, Small Heath, when a man burst in and violently struck him on the head.
The thug grabbed the youth’s phone before fleeing the building.
There were other worshippers inside the mosque who came to the injured boy’s aid.
The shocking incident happened just before 7 pm on Friday, February 1.
Reports on social media said the man was wearing a balaclava and the traumatised victim was escorted to hospital by police.
West Midlands Police are appealing for anyone with information to contact them urgently.
A force spokesman said: "Police are investigating an assault at a mosque in Tennyson Road, Small Heath, Birmingham which happened just before 7 pm on Friday (1 February).
“A 16-year-old boy was hit over the head by a man who stole his phone.”
Melissa Whitehouse wrote: "Just awful... he's just a boy...hope he's ok."
Parm Uppal said: "I hope lad get well soon. Also I hope police catch the robber.”
Shola Ogunlade posted: “Praying for healing.”