Mary … anointed Jesus' feet. This was not awkward because Jews reclined at formal meals, but it was still a dramatic gesture (compare Matthew 26:6–16; Mark 14:3–9).
Nard was a valuable spice from North India. It was sweet, red, and smelled like the perfume made from the gladiola plant. Twelve ounces of nard cost one year's wages (John 12:5).
According to Mark's Gospel, Mary also anointed the head of Jesus (Mark 14:3). The perfume ran down and made his clothes smell good (Mark 14:8).
her hair: Women never took their hair covering off in public (see Luke 7:38). Mary was acting with deep and costly devotion.