Tosefta do Przysłów 24:26

[With respect to] one who assigns in writing his possessions to his slave, [the slave] thereby goes free (Peah 3:8, following Kulp tr.). [But if] he reserved for himself any land, however small, he does not go free. Rabbi Shimon says, one who says, "I give all of my possessions to such-and-such slave, except for one-thousandth part of them," [it is as though] he did not say anything. [But if he said, "I give all of my possessions to such-and-such slave,] except for [my possessions in] such-and-such city or such-and-such field, even though he owns nothing but that field or [possessions] in that city, the slave has acquired these as his inheritance, and has acquired himself and become a free man. And when they said these words before Rabbi Yosei, he said (Proverbs 24:26), "Giving a straightforward reply is like giving a kiss."