Hadith: People were judged by the divine revelation during the lifetime of the Messenger of Allah (may Allah's peace and blessings be upon him) but the divine revelation has ceased. Now, we only judge you by what is apparent to us from your deeds. Whoever appears to be good, we trust and honor him, and what he does in secret is no concern of ours, for Allah will judge him for what he does in secret. Whoever appears to be evil, we will not trust or believe him.

عن عبد الله بن عتبة بن مسعود، قال: سمعت عمر بن الخطاب رضي الله عنه يقول: إن ناسا كانوا يُؤْخَذُونَ بالوحي في عهد رسول الله صلى الله عليه وسلم وإن الوحي قد انقطع، وإنما نأخذكم الآن بما ظهر لنا من أعمالكم، فمن أظهر لنا خيرًا أَمَّنَّاهُ وقَرَّبْنَاهُ، وليس لنا من سريرته شيء، الله يحاسبه في سريرته، ومن أظهر لنا سوءًا لم نأمنه ولم نصدقه وإن قال: إن سريرته حسنة.
[صحيح] - [رواه البخاري]

‘Abdullāh ibn ‘Utbah ibn Mas‘ūd reported: I heard ‘Umar ibn al-Khattāb (may Allah be pleased with him) say: "People were judged by the divine revelation during the lifetime of the Messenger of Allah (may Allah's peace and blessings be upon him) but the divine revelation has ceased. Now, we only judge you by what is apparent to us from your deeds. Whoever appears to be good, we trust and honor him, and what he does in secret is no concern of ours, for Allah will judge him for what he does in secret. Whoever appears to be evil, we will not trust or believe him, even if he says that his intentions are good."
[Authentic hadith] - [Narrated by Bukhari]

Explanation

‘Umar ibn al-Khattāb (may Allah be pleased with him) spoke about the one who concealed evil intentions at the time of divine revelation, and how that was made known to the Prophet (may Allah's peace and blessings be upon him) through the revelation. During the time of the Messenger of Allah (may Allah's peace and blessings be upon him) some people were hypocrites, pretending to be good while concealing evil. However, Allah, the Exalted, exposed them through the revelation to His Messenger (may Allah's peace and blessings be upon him). When the revelation ceased, people were incapable of knowing the hypocrites, because hypocrisy is in the heart. He thus said that they started judging people by what appears to them. So whoever appeared to be good, they dealt with him according to what he showed, even if he had evil intentions. Whoever appeared to be evil, they dealt with him according to the evil he showed, and they were not responsible for his intention. The intention is entrusted to the Lord of the Worlds, Exalted and Glorified, who knows what one's inner self whispers to him.