The Tosefta on Becoming a Ḥaver

2. [Regarding] one who takes upon himself four¹ things, they accept him as a ḥaver: not to give terumah (the priestly due) and tithes to [a priest who is] an ‘am ha-’arets, not to prepare foodstuffs requiring conditions of purity for an ‘am ha-’arets, and to eat unconsecrated food in a state of purity. [ . . . ]

10. One who comes to take upon himself [the obligations of ḥaverut]: If he had previously acted [according to them] in private, they accept him and afterward instruct him; and if not, they instruct him and afterward accept him.

R. Simeon says: In either case, they accept him and [then] instruct him as they go along.

11. And they accept [him first] with regard to “wings,”² and afterward they accept]him[with regard to foodstuffs that require preparation in conditions of cleanness.

If he said, “I take upon myself only [the obligations] regarding ‘wings,’” they accept him.

If he took upon himself [the obligations] regarding clean foodstuffs but did not take upon himself [the obligations] regarding “wings,” he is also not deemed trustworthy with regard to clean foodstuffs.

12. How long before they accept him?

The house of Shammai say: “For liquids, thirty days; for clothing, twelve months.”

The house of Hillel say: “For both, thirty days.”