Guru Brahma, Guru Vishnu, Guru devo Maheshwara
Guru sakshat, param Brahma, tasmai shri guravay namah

From https://jivamuktiyoga.com/fotm/guru-mantra/:
Our creation is that guru (Brahma-the force of creation); the duration of our lives is that guru (Vishnu-the force of preservation); our trials, tribulations, illnesses, calamities and the death of the body is that guru (devo Maheshwara-the force of destruction or transformation). There is a guru nearby (Guru Sakshat) and a guru that is beyond the beyond (param Brahma). I make my offering (tasmai) to the beautiful (shri) remover of my darkness, my ignorance; (Guru) it is to you I bow and lay down my life (namah).