Mishkat al-Masabih
Mishkat al-Masabih 1070
وَعَنْ ثَوْبَانَ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: " ثَلَاثٌ لَا يَحِلُّ لِأَحَدٍ أَنْ يَفْعَلَهُنَّ: لَا يَؤُمَّنَّ رَجُلٌ قَوْمًا فَيَخُصَّ نَفْسَهُ بِالدُّعَاءِ دُونَهُمْ فَإِنْ فَعَلَ ذَلِكَ فَقَدْ خَانَهُمْ. وَلَا يَنْظُرْ فِي قَعْرِ بَيْتٍ قَبْلَ أَنْ يَسْتَأْذِنَ فَإِنْ فَعَلَ ذَلِكَ فَقَدْ خَانَهُمْ وَلَا يُصَلِّ وَهُوَ حَقِنٌ حَتَّى يَتَخَفَّفَ ". رَوَاهُ أَبُو دَاوُدَ وللترمذي نَحوه
Unreviewed translation. All hadiths in this collection are available in five languages. Titles and introductions may remain in Arabic.
Thauban reported that the Messenger of Allah (ﷺ) said: There are three things that no one may do. A man must not lead people in prayer and single himself out in supplication to the exclusion of the others; if he does, he has betrayed them. He must not look inside a house before asking permission; if he does, he has betrayed its occupants. And he must not pray while holding back urine until he has relieved himself. Abu Dawud transmitted it; al-Tirmidhi transmitted a similar report.
Notes and open questions — unreviewed
The source lists three prohibitions: exclusive supplication by an imam, looking into a house before permission, and praying while needing to relieve oneself.