“Self is the only prison that can ever bind the soul.”

Dostoievsky’s barrack vows of “improvement” now appeared to him as a sacrilege. He experience which he underwent was much the same as Luther’s when he remembered with such unfeigned horror and disgust the vows which he had pronounced on entering the convent. P. 10
Source: In Job's Balances: on the sources of the eternal truths, The Conquest of the Self-Evident; Dostoievsky’s Philosophy

7 - 10
Auxiliaries to the Perception of Intelligible Natures
Context: The soul is bound to the body by a conversion to the corporeal passions; and again liberated by becoming impassive to the body.
That which nature binds, nature also dissolves: and that which the soul binds, the soul likewise dissolves. Nature, indeed, bound the body to the soul; but the soul binds herself to the body. Nature, therefore, liberates the body from the soul; but the soul liberates herself from the body.
Hence there is a twofold death; the one, indeed, universally known, in which the body is liberated from the soul; but the other peculiar to philosophers, in which the soul is liberated from the body. Nor does the one entirely follow the other.
We do not understand similarly in all things, but in a manner adapted to the essence of each. For intellectual objects we understand intellectually; but those that pertain to soul rationally. We apprehend plants spermatically; but bodies idolically (i. e., as images); and that which is above all these, super-intellectually and super-essentially.

The Clod and the Pebble, st. 3
1790s, Songs of Experience (1794)
Source: Songs of Innocence and Songs of Experience

[L]'âme, prison du corps.
Discipline and Punish (1977) as translated by Alan Sheridan, p. 30
Discipline and Punish (1977)

"The Monument of Giordano Bruno", inspired by the statue in memory of Giordano Bruno at the place where he was burned as a heretic.
Astrophel and Other Poems (1894)
Context: Not from without us, only from within,
Comes or can ever come upon us light
Whereby the soul keeps ever truth in sight.
No truth, no strength, no comfort man may win,
No grace for guidance, no release from sin,
Save of his own soul's giving.

Letter XVIII.
Letters

Discipline and Punish (1977)
Context: The man described for us, whom we are invited to free, is already in himself the effect of a subjection much more profound than himself. A 'soul' inhabits him and brings him to existence... the soul is the effect and instrument of political anatomy; the soul is the prison of the body.
Context: But let there be no misunderstanding: it is not that a real man, the object of knowledge, philosophical reflection or technological intervention, has been substituted for the soul, the illusion of theologians. The man described for us, whom we are invited to free, is already in himself the effect of a subjection more profound than himself. A 'soul' inhabits him and brings him to existence, which is itself a factor in the mastery that power exercises over the body. The soul is the effect and instrument of a political anatomy; the soul is the prison of the body.

About Tolerance (1977)

Willis, The Scholar of Thibét Ben Khorat, II. Quote reported in Hoyt's New Cyclopedia Of Practical Quotations (1922), p. 419-23.