Reference for Menachot 13:1

הֲרֵי עָלַי עִשָּׂרוֹן, יָבִיא אֶחָד. עֶשְׂרוֹנִים, יָבִיא שְׁנָיִם. פֵּרַשְׁתִּי וְאֵינִי יוֹדֵעַ מַה פֵּרַשְׁתִּי, יָבִיא שִׁשִּׁים עִשָּׂרוֹן. הֲרֵי עָלַי מִנְחָה, יָבִיא אֵיזוֹ שֶׁיִּרְצֶה. רַבִּי יְהוּדָה אוֹמֵר, יָבִיא מִנְחַת הַסֹּלֶת, שֶׁהִיא מְיֻחֶדֶת שֶׁבַּמְּנָחוֹת:

[One who says,] "I take upon myself an <i>issaron</i> [specific dry volume measure]" - he must bring one. "<i>esronim</i>" - he must bring two. "I specified, but I don't know what I specified" - he must bring 60 <i>issaron</i>. If he said, "I take upon myself a grain offering" - he may bring whichever type he wants. Rabbi Yehuda says: he should bring a fine-flour grain offering, because it is the most special of the grain offerings.

Jastrow