The 252nd prohibition is that we are further forbidden from verbally causing emotional distress to a convert, i.e., ona'as devarim.
The source of this prohibition is G‑d's statement1 (exalted be He), "Do not wrong a convert."
In the words of the Mechilta: "The verse 'Do not wrong a convert' means doing so with your words." This prohibition is repeated a second time, in the phrase "[When a convert comes to live in your land,] do not hurt his feelings.' "
In the words of the Sifra: "You should not tell him, 'Yesterday you were an idolater and now you have entered under the wings of the Divine Presence.' "
