Bereshit 18:19 starts with the words 'For I have known him (כִּי יְדַעְתִּיו)', the Sefaria website translates these words as 'For I have singled him out', Rashi as 'I know him intimately'. In line with these I also found: 'For I know him, that he will...' and 'I have given him special attention so that he will...' The focus here seems to lay on the idea Avraham is given a special role or special attention in order for him to teach his children and his household after him to keep the way of Adonai.
I'm familiar with the meaning of the root ידע. But I noticed the word יְדַעְתִּיו only occurs once in the whole Tenach. I'm not so familiar with all the grammar rules, but I noticed in my dictionary the following under the root, יֻדַּע ,ידע; to be told, to be made aware, to be informed, to become familiar with.
This is why I wondered if there is a possibility to render or understand this verse as: For I have told him, taught him, made him aware, informed him, so that he would teach etc.. in order to teach it seems logical that Avraham 'learned' and 'got familiar with', 'got knowledge of' the ways of Adonai, and it would also fit with Bereshit 26:5 Avraham hearkened to My voice, and kept My charge, My commandments, My statutes, and My laws.. which he would teach his children and his household after him. It would also add to the idea that Avraham is given a special role or special attention in order for him to teach.
Should I understand these words כִּי יְדַעְתִּיו , to have such meaning? Is it a idiom to express such a thing?