[26a middle] Gemarah: The Mishna is not in accordance with Rebbi’s view. Rebbi maintains that with just two occurrences, a legal presumption is established [ie: a woman twice widowed or divorced is one whose husbands can be expected to die “Katlonis” or divorce her (and should therefore not be remarried)], whereas the Mishna seems to allow this kind of woman to be married to again.
i loved this Prac-T-cal Tidbits: All of our actions can demonstrate different principles and standards even if done only twice. If we desire to establish good routines (i.e. to make it to a certain Minyan everyday), we must be sure to keep them at least two days in a row to get the (good) habits going.