Don't get distracted verse 11: 

'but thou O man of God' (v11) 

12 disciples, 1 failed, was removed and was replaced by Matthias in Acts 1:25. 

Men of God – 12 in the OT: 

Moses – a man who gave the law of God (Ezra 3:2; 2 Chron 30:16), who blessed the people of God, in fact he left them with blessing (Deuteronomy 33:1). 
Angel of God appearing to Manoah, whose name is 'Wonderful,' (Judges 13:6,8) – a possible Christophany. 
Unnamed Man of God who brings a prophetic word of judgment and condemnation to Eli (1…