A sure peg, a peg that shall not give way
Figuratively: a secure hold; something that can be relied on; a sure support (in the original, yated means a large nail).
("I will fasten him as a peg in a sure place, and he shall be for a throne of glory to his father's house" - Isaiah 22:23)
Translation
Expression (Hebrew)
יָתֵד נֶאֱמָן, יָתֵד שֶׁלֹּא תִּימּוֹט
Definition (Hebrew)
בְּהַשְׁאָלָה: אֲחִיזָה בְּטוּחָה. דָּבָר שֶׁנִּיתָּן לִסְמֹוךְ עָלָיו. מִשְׁעֶנֶת בְּטוּחָה (בַּמָּקוֹר יָתֵד מַשְׁמָע מַסְמֵר גָּדוֹל).
("וּתְקַעְתִּיו יָתֵד בְּמָקוֹם נֶאֱמָן וְהָיָה לְכִסֵּא כָבוֹד לְבֵית אָבִיו"- יְשַׁעְיָהוּ כב כג)