There are those who present it in this wording: There we learned, a virgin marries on the fourth day and a widow on the fifth day. Why? Because a blessing is written concerning them. But is not a blessing written only on the fifth for the fish and on the sixth for the man? Bar Kappara says: The fourth day is the eve [the night-light] of the fifth, and the fifth is the eve of the sixth.
A Second Version of the Teaching on Wedding Days
Yalkut Shimoni on Torah 16:5
אִיתְ דְּמַפְקִין בְּהַאי לִישְׁנָא, תַּמָּן תָּנֵינָן בְּתוּלָה נִשֵּׂאת לַיּוֹם הָרְבִיעִי וְאַלְמָנָה לַיּוֹם הַחֲמִישִׁי, לָמָּה, שֶׁכָּתוּב בָּהֵן בְּרָכָה וַהֲלֹא אֵין כְּתִיב בְּרָכָה אֶלָּא בַּחֲמִישִׁי לַדָּגִים וּבַשִּׁשִּׁי לָאָדָם בַּר קַפָּרָא אוֹמֵר, רְבִיעִי אוֹר לַחֲמִישִׁי חֲמִישִׁי אוֹר לַשִּׁשִּׁי.