John Gill Commentary John 12:3

"Mary therefore took a pound of ointment of pure nard, very precious, and anointed the feet of Jesus, and wiped his feet with her hair: and the house was filled with the odor of the ointment." — John 12:3 (ASV)

Then took Mary a pound of ointment of spikenard very costly ,
&c.] Worth three hundred pence, according to Judas's estimation of it. This Mary was the other sister of Lazarus; (See Gill on Matthew 26:7), (See Gill on Mark 14:3), concerning the nature and value of this ointment:

and anointed the feet of Jesus ;
as he lay upon the bed or couch, at supper:

and wiped his feet with her hair; (See Gill on Luke 7:38).

And the house was filled with the odour of the ointment ;
see (Song of Solomon 1:3Song of Solomon 1:12) ; ointment of spikenard was very odoriferous: this may be an emblem of the sweet savour of Christ, in the ministration of the Gospel, throughout the whole world.