The Russian Primary Chronicle writes that he "was kindly toward the poor and hospitable to strangers, zealous toward the church, warm in faith, peaceful, and fair in appearance".

[10][11][12] According to the Life of Feodosy, the citizens of Tmutorakan requested the monk Nikon the Great to persuade Sviatoslav Iaroslavich to again appoint Gleb as their prince.

[13] According to the inscription of the "Stone of Tmutarakan", Gleb had the width of the frozen Strait of Kerch measured in the winter of 1067-68.

[19] According to the Hypatian version of the Russian Primary Chronicle, Gleb visited his father in Kiev and witnessed the death of the saintly Abbot Feodosy of the Monastery of the Caves in 1074.

[21] A late source—Vasily Tatishchev's compilation of medieval chronicles—writes that Sviatoslav Iaroslavich appointed Gleb and Vladimir Monomach to command the Rus' troops sent to fight against the Bulgarians at Cherson upon the request of the Byzantine Emperor Michael VII Ducas, but the source's reliability is doubtful.

[22] The Russian Primary Source narrates that a "magician" (a volkhv)[23] arrived in Novgorod and stirred up the townsfolk against the bishop.

[25] Gleb dared the volkhv who had stated that he could foretell the future to predict "what was about to happen that very day",[23] according to the Russian Primary Chronicle.