For logic would have dictated: that if the first testimony, which does not render her permanently forbidden, cannot be estab-lished by less than two [witnesses] —- [then] the last testimony, which does render her permanently forbidden, should cer-tainly not be established by less than two [witnesses]! But [the Torah] teaches (Numbers 5:13): And there was none to testify against her —- any manner of testimony which there may be against her.  But now [the logic of] kal vachomer dic-tates in regard to the first testimony: that if the last testimony, which does render her permanently forbidden, can yet be es-tablished by one witness —- [then] the first testimony, which does not render her permanently forbidden, should certainly be established by one witness! But [the Torah] teaches (Deut. 24:1): for he found in her some immoral matter, and over there (Deut. 19:15) it says: By the testimony of two witnesses ... shall a matter be established —- just as over there it is by the testimony of two witnesses, here too it is by the testimony of two witnesses.