The University of Virginia publishes many of Thomas Jefferson's quotes. On the page linked below you see his quotes regarding the need for the Bill of Rights.
Jefferson is quoted very often today because of his metaphor "separation of church and state." This was intended as s single-purpose metaphor describing an aspect of the religion clauses of the First Amendment. However, in many of his writings where he talks more generally about the need of the Bill of Rights, he doesn't mention the Establishment Clause of the First Amendment. He seems to focus on the Free Exercise instead. On the page below you will find the phrase "freedom of religion" used six times, but you will not find "separation of church and state" even once.