It is supposed that among the Shinagon, Tadanobu was closest to Michinaga, and he also accompanied Michinaga, who had already entered the priesthood, when he went to Arima-Onsen Hot Spring for medical treatment and recuperation in 1024.
四納言のうち、もっとも道長と親しかったのは斉信であったと考えられ、道長が出家後の万寿元年（1024年）に病気療養のために有馬温泉に向かった際に斉信も同行している。