Among the prohibitions for which one is liable to receive the punishment of karet is ha-mefatem et ha-shemen – someone who prepares the shemen ha-mish’ḥa for personal use.
What was this shemen ha-mish’ḥa, this anointing oil?
The Torah teaches that a unique anointing oil must be prepared to consecrate the mishkan – the Tabernacle – and its vessels (see Sefer Shemot 30:22-33) as well as the High Priest, Aharon HaKohen and his children. Our Gemara teaches that the kings of Israel were also anointed, although there was no need to anoint a king who replaced his father in peaceful succession.
The Gemara quotes a baraita where Rabbi Yehuda teaches that the oil was prepared by boiling the roots of the spices in it. Rabbi Yosei objects that the amount of oil was not sufficient even to apply to the roots (they would absorb the oil), so they could not possibly have boiled in it. Rather, the roots were placed in water where they were boiled, the fragrant substance would rise to the top, and one poured the anointing oil on the water where it would absorb the fragrance. Later he removed the oil from the top and placed it in a flask. Rabbi Yehuda responded that there were many miracles in the production and use of the oil. Although only 12 lugin were produced, it sufficed to anoint all of the vessels in the mishkan as well as Aharon and his sons throughout the week of dedication of the Tabernacle. Furthermore, based on the passage in Sefer Shemot (30:31), the oil remained for use at the end of days.
One of the ingredients in making this oil, tzori, may be identified as the plant Commiphora apobalsamum, from which balsam oil is taken. The highest quality perfume drips from the plants, but most of the perfume is extracted by means of boiling its branches. When such oil was used for medicinal purposes, its main use was for incense and fragrant oil. During the time of the Mishna it was literally worth its weight in gold.
In the late 20th century, such oil was found in a cave near the Dead Sea.