“Oh! May God send us poverty; may God send us lack of means, and take away our power of speech if it must be, and help us only to stammer, if we may only thus get the [anointing]. Oh! I rave to be useful to souls, and all the rest may go where it will.” (Spurgeon)

Anointed ones is literally Sons of Oil. In Hebrew idioms the son of something is radically characterized by that thing...the [Anointed ones] are so characterized by the ministry and the power of the Holy Spirit that they are literally Sons of Oil.

excerpts from:
Zechariah 4 - By My Spirit, Says the LORD