Joseph Frank makes this note in the inaugural volume of his widely celebrated literary biography, Dostoevsky: The Seeds of Revolt, 1821-1849 (1979), 54:

Many years later, when Dostoevsky was reading the Book of Job once again — as he had done so many times before — he wrote his wife that it put him into such a state of “unhealthy rapture” that he almost cried. “It’s a strange thing, Anya, this book is one of the first in my life which made an impression on me; I was then still almost a child.”

There is an allusion to this revelatory experience of the young boy in The Brothers Karamazov, where Father Zosima recalls being struck by a reading of the Book of Job at the age of eight, and feeling that “for the first time in my life I consciously received the seed of God’s word in my heart.”

In other words, it is quite possible Zosima’s childhood experience is autobiographical for Fyodor Dostoyevsky. In light of that point, here’s the reference in The Brothers Karamazov, Pevear/Volokhonsky translation (2002), 291:

Mother took me to church by myself (I do not remember where my brother was then), during Holy Week, to the Monday liturgy. It was a clear day, and, remembering it now, I seem to see again the incense rising from the censer and quietly ascending upwards, and from above, through a narrow window in the cupola, God’s rays pouring down upon us in the church, and the incense rising up to them in waves, as if dissolving into them. I looked with deep tenderness, and for the first time in my life I consciously received the first seed of the word of God in my soul.

A young man walked out into the middle of the church with a big book, so big that it seemed to me he even had difficulty carrying it, and he placed it on the analogion, opened it, and began to read, and suddenly, then, for the first time I understood something, for the first time in my life I understood what was read in God’s church.

There was a man in the land of Uz, rightful and pious, and he had so much wealth, so many camels, so many sheep and asses, and his children made merry, and he loved them very much and beseeched God for them: for it may be that they have sinned in their merrymaking. Now Satan goes up before God together with the sons of God, and says to the Lord that he has walked all over the earth and under the earth.

“And have you seen my servant Job?” God asks him.

And God boasted before Satan, pointing to his great and holy servant.

And Satan smiled at God’s words: “Hand him over to me and you shall see that your servant will begin to murmur and will curse your name.”

And God handed over his righteous man, whom he loved so, to Satan, and Satan smote his children and his cattle, and scattered his wealth, all suddenly, as if with divine lightning, and Job rent his garments and threw himself to the ground and cried out: “Naked came I out of my mother’s womb, and naked shall I return into the earth: the Lord gave and the Lord has taken away: blessed be the name of the Lord henceforth and forevermore!”

Fathers and teachers, bear with these tears of mine — for it is as if my whole childhood were rising again before me, and I am breathing now as I breathed then with my eight-year-old little breast, and feel, as I did then, astonishment, confusion, and joy.