My head with oil - The custom of pouring oil upon the head was universal among the Jews. The oil used was sweet oil or oil of olives, prepared in such a way as to give an agreeable smell. It was also used to render the hair more smooth and elegant. See Ruth 3:3; 2-Samuel 12:20; 2-Samuel 14:2; Psalm 23:5.
With ointment - This "ointment" was a mixture of various aromatics, and was therefore far more costly and precious than the "oil" commonly used for anointing the head. Her conduct, compared with that of Simon, was therefore more striking. "He" did not give even the common oil "for his head" used on such occasions. "She" had applied to "his feet" a far more precious and valuable "unguent." "He" therefore, showed comparatively "little" love. "She" showed "much."

My head with oil thou didst not anoint - Anointing the head with oil was as common among the Jews as washing the face with water is among us. See Ruth 3:3; 2-Samuel 12:20; 2-Samuel 14:2; 2-Kings 4:2; and Psalm 23:5, where the author alludes to the Jewish manner of receiving and entertaining a guest. Thou preparest a table for me; anointest my head with oil; givest me an overflowing cup. See Matthew 5:17.

Mine head with oil thou didst not anoint,.... No not with common oil, so usually done at feasts, see Psalm 23:5
but this woman hath anointed my feet with ointment; even "with ointment" "of spices", as the Syriac version renders it. There is, throughout the whole account, an opposition between the conduct of Simon, and this woman: he gave him no common water to wash his feet with, she shed floods of tears, and with them bathed his feet, and then wiped them clean with the hairs of her head; he gave him not the usual salutation by kissing his head or lips, but she kissed his feet, and that over and over again; he did not so much as anoint his head with common oil, when she anointed his feet with costly ointment brought in an alabaster box. These several ceremonies to guests were used by their hosts, in other nations, such as washing, anointing, and kissing (c).
(c) Vid. Apuleii Metamorph. i. 1. prope finem.

with oil . . . not anoint--even common olive oil in contrast with the woman's "ointment" or aromatic balsam. What evidence was thus afforded of any feeling which forgiveness prompts? Our Lord speaks this with delicate politeness, as if hurt at these inattentions of His host, which though not invariably shown to guests, were the customary marks of studied respect and regard. The inference is plain--only one of the debtors was really forgiven, though in the first instance, to give room for the play of withheld feelings, the forgiveness of both is supposed in the parable.