I Samuel 2:18 Kabbalah

וּשְׁמוּאֵ֕ל מְשָׁרֵ֖ת אֶת־פְּנֵ֣י יְהוָ֑ה נַ֕עַר חָג֖וּר אֵפ֥וֹד בָּֽד׃

But Samuel ministered before the LORD, being a child, girded with a linen ephod.

Read kabbalistic (mystical) interpretation of I Samuel 2:18: and classical mystical sources.