Pesachim 106b
פסחים ק״ו ב — ד"ה הַנּוֹטֵל יָדָיו לֹא יְקַדֵּשׁ
Pesachim 106b:1
Chachmei Bavel report a dispute about whether one who has washed his hands may recite kiddush, presenting Rav’s practice of sometimes washing and reciting kiddush over bread and at other times reciting kiddush over wine as evidence that kiddush is not an interruption before eating.
הַנּוֹטֵל יָדָיו לֹא יְקַדֵּשׁ. אֲמַר לְהוּ רַב יִצְחָק בַּר שְׁמוּאֵל בַּר מָרְתָא: אַכַּתִּי לָא נָח נַפְשֵׁיהּ דְּרַב שְׁכַחְנִינְהוּ לִשְׁמַעְתְּתֵיהּ. זִמְנִין סַגִּיאִין הֲוָה קָאֵימְנָא קַמֵּיהּ דְּרַב, זִימְנִין דַּחֲבִיבָא עֲלֵיהּ רִיפְתָּא — מְקַדֵּשׁ אַרִיפְתָּא. זִימְנִין דַּחֲבִיבָא לֵיהּ חַמְרָא — מְקַדֵּשׁ אַחַמְרָא.
One who washes his hands should not recite kiddush after washing, as this would constitute an interruption between washing and eating, and he will have to wash again. Instead, he should hear kiddush from someone else. Rav Yitzḥak bar Shmuel bar Marta said to them: Not a lot of time has yet passed since Rav died, and we have already forgotten his halakhic rulings. Many times I stood before Rav and saw that sometimes he preferred bread, and he would recite kiddush over bread. On those occasions Rav would wash his hands, recite kiddush over the bread, and eat it. At other times he preferred wine and would recite kiddush over wine. This shows that kiddush is not considered an interruption between washing one’s hands and eating bread.