From the teachings of our holy father Abba Ammon
There are four things, even if a person possesses one of them, he cannot repent, and God will not accept his prayers.
1. The first is pride: when a person thinks that he lives correctly, that his life is pleasing to God, that in his conversations he edifies many and that [some people], having retired to the desert, [thanks to him] were delivered from many sins; if a person thinks so, then God does not dwell in him 150 .
On the contrary, a monk should judge himself with a more severe judgment than that of foolish people, and not consider his deeds pleasing to God. For it is said by the prophet: "All the righteous acts of man are as filthy rags before Him" ( Isaiah 64:6 ) . 151 And if the soul is not truly convinced that it is more impure than foolish creatures, such as birds or dogs, then God will not accept its prayer. For foolish creatures, such as dogs or birds, never sin before God and will not be judged by Him. From this it is clear that a sinful man is more pitiable than beasts, since he, unlike foolish creatures, is destined for resurrection from the dead and will appear before God's Judgment . 152 For foolish creatures do not speak evil or take pride, but love those who feed them, but man does not love, as he should, God, who created and feeds him.
2. The second thing is: if someone harbors a grudge against someone, even if he were to blind that person, he would still not forgive them for the evil. The prayer of such a vindictive person does not ascend to God. And let him not delude himself: even if he were to resurrect the dead, he will not attain mercy and forgiveness from God.
3. Thirdly, if anyone condemns a sinner, he himself will be condemned, even if he performs signs and wonders. For Christ said, "Judge not, that ye be not judged" ( Matthew 7:1 ). Therefore, a Christian should not condemn anyone, "for even the Father judges no one, but has committed all judgment to the Son" ( John 5:22 ). Therefore, anyone who judges before Christ is an antichrist . 154 And many who are robbers and fornicators today will be found saints and righteous tomorrow.
4. The fourth thing is, if anyone does not have love; without it, as the apostle says, even if we spoke with the tongues of angels, had all the right faith, moved mountains, distributed all our goods to the poor, and gave up our bodies to be martyred – [all this without love] brings us no benefit ( 1 Cor. 13:1-3 ). But you will say: “How can anyone give all his goods to the poor and not have love? Is not almsgiving love?” No. Almsgiving is not perfect love, but is [only] one of the manifestations of love 155 . For many give alms to some, and offend others; show hospitality to some, and bear a grudge against others; defend some, and slander others; show compassion to strangers, and hate their own. This is not love, for love hates no one, blasphemes no one, condemns no one, grieves no one, disdains no one—neither believers nor unbelievers, nor strangers, nor sinners, nor fornicators, nor the unclean. But, on the contrary, it loves sinners, the weak, and the negligent; for their sakes it suffers, grieves, and weeps. [Even more]: it rather sympathizes with the wicked and sinful, imitating Christ, who called sinners and ate and drank with them ( Matt. 9:11-13 ). Therefore, showing what true love is, He teaches [us]: “Be good and merciful, as your Father in heaven.” And just as He sends rain on the evil and the good, and makes the sun rise on the just and the unjust ( Matthew 5:45 ), so those who have true love love everyone, pity everyone, and pray for everyone. Some give alms and, relying solely on it, commit a multitude of sins, hate many, and defile their bodies with impure lusts. Such [people] deceive themselves, relying [only] on the alms they believe they give.
Source: https://azbyka.ru/otechnik/Aleksej_Sidorov/tvorenija-drevnikh-ottsov-podvizhnikov/1_3_1