Reference for Sanhedrin 101:16
סד"א (ויקרא כא, ט) כי תחל לזנות אמר רחמנא הני מילי היכא דקא מתחלא השתא אבל הא כיון דקא מתחלא וקיימא מעיקרא
'The daughter of any priest: from this phrase I know the law only if shewas married to a priest; if she was married to a Levite, Israelite, heathen,a profaned person, bastard, or a Nathin, whence do I know that the same applies?From the verse: And the daughter of a man who is a priest, which teachesthat even if she is married to one who is not a priest the same applies.'But because she is married to one of these, is she no longer considered apriest's daughter? Moreover, does Scripture state … a priest's daughtermarried to a priest?<span class="x" onmousemove="('comment',' I.e., on what grounds could we assume at all that the law is applicable only if she married a priest? ');"><sup>14</sup></span>