Prohibition of spying

It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that a man came to him and said: "What do you say about al-Walid bin Uqbah, while drops of wine are dripping from his beard?" He said: "The Messenger of Allah (peace and blessings be upon him) forbade us from spying (probing to uncover faults); but if some offence becomes apparent to us (without spying), we will take him to account for it."
This hadith is sahih al-isnad (its chain is authentic), but the two Shaykhs (Bukhari and Muslim) did not record it.

It is narrated from Sayyiduna Abd al-Rahman bin Awf (may Allah be pleased with him) that he kept watch one night with Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) in Madinah. As they were walking, they suddenly saw a lamp burning in a house, so they went towards it until, when they came near, they saw that the door was closed and from inside came the noise of people's loud voices. Sayyiduna Umar (may Allah be pleased with him) took Sayyiduna Abd al-Rahman (may Allah be pleased with him) by the hand and said: "Do you know whose house this is?" He said: "No." He said: "This is the house of Rabi'ah bin Umayyah bin Khalaf, and they are drinking wine right now. So what is your view?" Sayyiduna Abd al-Rahman (may Allah be pleased with him) said: "My view is that we have committed what Allah has forbidden; Allah, the Mighty and Majestic, forbade us, saying: 'And do not spy' [Surah al-Hujurat: 12], and we have spied." So Sayyiduna Umar (may Allah be pleased with him) turned back from them and left them alone.
This hadith is sahih al-isnad (its chain is authentic), but the two Shaykhs (Bukhari and Muslim) did not record it.