He answers with yes and no, and his opinion is weak
He answers both yes and no at once. The matter is not clear to him.
("They asked Rav Yehuda: What about the upper weight and the lower weight? He answered: 'Yes and no, and it is weak in his hand.'" - Shabbat 113a)
Translation
Expression (Hebrew)
אִין וְלָאו וְרַפְיָא בִּידֵהּ
Definition (Hebrew)
מֵשִׁיב בְּכֵן וְלֹא כְּאֶחָד. הַדָּבָר אֵינוֹ בָּרוּר עַל יָדוֹ.
("בְּעוּ מִנֵּיהּ מֵרַב יְהוּדָה: כֹּבֶד הָעֶלְיוֹן וְכֹבֶד הַתַּחְתּוֹן מַהוּ: אִין וְלָאו וְרַפְיָא בִּידֵהּ"- שַׁבָּת קיג ע"א)