The golem begins as a theological problem rather than a monster story, and its earliest materials are terse.
The word golem occurs once in the Hebrew Bible, in Psalm 139, where it means something unformed or embryonic, the psalmist's unshaped substance seen by God. Rabbinic usage extends it to any incomplete or unfinished thing, including, notably, Adam in the hours before he received a soul.
The Babylonian Talmud supplies the founding anecdote in tractate Sanhedrin. Rava creates a man and sends him to Rabbi Zeira, who speaks to him; the creature does not answer, and Zeira tells him to return to his dust. The passage is a few lines long. It establishes three things that the whole later tradition works with: that a human being can make such a creature, that its defining lack is speech, and that it can be unmade by a word.
The technique is associated with the Sefer Yetzirah, the short and difficult Book of Formation, which describes creation through the twenty-two letters of the Hebrew alphabet and the ten sefirot. Medieval commentators, particularly among the Hasidei Ashkenaz, the German pietists of the twelfth and thirteenth centuries, developed rituals of letter permutation understood as reproducing the divine act of creation in miniature. Critically, these were treated as contemplative exercises. The point was to experience the creative power of language, not to obtain a servant, and the creature was normally undone immediately.