NKJV 365 Day Reading Planနမူနာ

very costly oil: Judas Iscariot said that this oil cost three hundred denarii (v. 5). One denarius was a laborer’s wage for one day (see Matt. 20:2). Thus the oil cost approximately a year’s wages. anointed the feet: Mary also anointed Jesus’ head (see Matt. 26:7; Mark 14:3). The custom of that time was to anoint the heads of guests. Anointing Jesus’ head was an act of honor; anointing His feet was a display of devotion.

Taken from NKJV Study Bible