In the Gemara, the shamir (Hebrew: שָׁמִיר‎ šāmīr) is a worm or a substance that had the power to cut through or disintegrate stone, iron and diamond. King Solomon is said to have used it in the building of the First Temple in Jerusalem in the place of cutting tools. For the building of the Temple, which promoted peace, it was inappropriate to use tools that could also cause war and bloodshed.

Referenced throughout the Talmud and the Midrashim, the Shamir was reputed to have existed in the time of Moses, as one of the ten wonders created on the eve of the first Sabbath, just before YHWH finished creation. Moses reputedly used the Shamir to engrave the Hoshen (Priestly breastplate) stones that were inserted into the High Priest's breastplate. King Solomon, aware of the existence of the Shamir, but unaware of its location, commissioned a search that turned up a "grain of Shamir the size of a barley-corn".

Solomon's artisans reputedly used the Shamir in the construction of Solomon's Temple. The material to be worked, whether stone, wood or metal, was affected by being "shown to the Shamir." Following this line of logic (anything that can be 'shown' something must have eyes to see), early Rabbinical scholars described the Shamir almost as a living being. Other early sources, however, describe it as a green stone. For storage, the Shamir was meant to have been always wrapped in wool and stored in a container made of lead; any other vessel would burst and disintegrate under the Shamir's gaze. The Shamir was said to have been either lost or had lost its potency (along with the "dripping of the honeycomb") by the time of the destruction of the First Temple at the hands of Nebuchadnezzar in 586 B.C.