Samuel feared to show Eli - He reverenced him as a father, and he feared to distress him by showing what the Lord had purposed to do. It does not appear that God had commanded Samuel to deliver this message: he, therefore, did not attempt it till adjured by Eli, 1 Samuel 3:17.
Opened the doors - We learn thus incidentally the nature of some of Samuel‘s duties. This duty was quite Levitical in its character. In the interval between Josh and David, when the tabernacle was stationary for the most part, it may have lost something of its “tent” character, and among other changes have had doors instead of the hanging.
Samuel feared to show Eli the vision - Here was Samuel‘s first experience of the prophet‘s cross: the having unwelcome truth to divulge to those he loved, honored, and feared. Compare the case of Jeremiah Jeremiah 15:10; Jeremiah 17:15-18; Jeremiah 20:7-18.