staycatholic.com/ecf_contraception.htm
John Chrysostom
[l]n truth, all men know that they who are under the power of this disease [the sin of covetousness] are wearied even of their father’s old age [wishing him to die so they can inherit]; and that which is sweet) and universally desirable,
the having of children, they esteem grievous and unwelcome. Many at least with this view have even paid money to be childless, and have mutilated nature, not only killing the newborn,
but even acting to prevent their beginning to live [sterilization] (Homilies on Matthew 28:5 [A.D. 391]).
NFP is acting to prevent the beginning of life. The cycle is watched and deliberately not having sex during the fertile period is preventing the life to begin.
Why do you sow where the field is eager to destroy the fruit, where there are medicines of sterility [oral contraceptives], where there is murder before birth?. . . Indeed, it is something worse than murder, and I do not know what to call it; for she does not kill what is formed but prevents its formation. What then? Do you condemn the gift of God and Fight with his [natural] laws? (Homilies on Romans 24 [A.D. 391]).
Jerome
In the above quote, Jerome is speaking of ABC and not NFP. It’s a given that ABC is sinful.
But I wonder why he [the heretic Jovinianus] set Judah and Tamar before us for an example, unless perchance even harlots give him pleasure; or Onan, who was slain because he grudged his brother seed. Does he imagine that we approve of any sexual intercourse except for the procreation of children? (Against Jovinian 1:19 [A.D. 393]).
Again, those using NFP are also having intercouse with the intent of not procreating children. In that case, NFP is sinful.
You may see a number of women who are widows before they are wives. Others, indeed, will drink sterility [oral contraceptives] and
murder a man not yet born, [and some commit abortion] (Letters 22:13 [A.D. 396]).
Augustine
The above quote is once again not about NFP.
This proves that you [Manicheans] approve of having a wife, not for the procreation of children, but for the gratification of passion. In marriage, as the marriage law declares, the man and woman come together for the procreation of children. Therefore, whoever makes the procreation of children a greater sin than copulation, forbids marriage and makes the woman not a wife but a mistress, who for some gifts presented to her, is joined to the man to gratify his passion (The Morals of the Manichees 18:65 [A.D. 388]).
You [Manicheans] make your auditors adulterers of their wives when they take care lest the women with whom they copulate conceive. They take wives according to the laws of matrimony by tablets announcing that the marriage is contracted to procreate children; and then, fearing because of your [religious] law [against childbearing] . . . they copulate in a shameful union only to satisfy lust for their wives. They are unwilling to have children, on whose account alone marriages are made. How is it, then, that you are not those prohibiting marriage, as the apostle predicted of you so long ago *, when you try to take from marriage what marriage is? When this is taken away, husbands are shameful lovers, wives are harlots, bridal chambers are brothels, fathers-in-law are pimps (Against Faustus 15:7 [A.D. 400]).
For thus the eternal law, that is, the will of God creator of all creatures, taking counsel for the conservation of natural order, not to serve lust, but to see to the preservation of the race, permits the delight of mortal flesh to be released from the control of reason in copulation only to propagate progeny (ibid. 22:30).*