The righteous have their 'yes' as 'yes' and their 'no' as 'no'/ an honest man's word is as good as his bond
The words of the righteous are established. We can trust what a righteous person says.
("And my daughter-in-law said - Rabbi Huna, in the name of Rabbi Shmuel, son of Rav Yitzhak: The righteous - these are theirs, these are theirs, and this is theirs, this is theirs, as it is said, "The man will not be silent, for if the matter is finished today" - Ruth Rabbah (Vilna), Parsha 7, 18)
Translation
Expression (Hebrew)
הַצַּדִּיקִים "הֵן" שֶׁלָּהֶן "הֵן" וְ"לָאו" שֶׁלָּהֶן "לָאו"
Definition (Hebrew)
דִּבְרֵי הַצַּדִּיקִים מִתְקַיְּמִים. נִתָּן לִסְמֹךְ עַל מָה שֶׁאוֹמֵר אָדָם צַדִּיק.
("וַתֹּאמֶר שְׁבִי בָּתֵּי- רַבִּי הוּנָא בְּשֵׁם רַבִּי שְׁמוּאֵל בַּר רַב יִצְחָק: הַצַּדִּיקִים- הֵן שֶׁלָּהֶן הֵן, וְלָאו שֶׁלָּהֶן לָאו שֶׁנֶּאֱמַר כִּי לֹא יִשְׁקֹט הָאִישׁ כִּי אִם כִּלָּה הַדָּבָר הַיּוֹם"- רוּת רַבָּה (וִילְנָא) פָּרָשָׁה ז , וְ-יח)