Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
Qurʾān Bukhārī Muslim Nasāʾī Abū Dāwūd Tirmidhī Ibn Mājah Mālik Aḥmad Dārimī Ḥākim Ibn Ḥibbān Ṭabarānī Nasāʾī's Kubrá Bayhaqī al-Luʾluʾ wa-al-Marjān Ibn Rajab's Fifty Riyāḍ al-Ṣāliḥīn Aḥmad's Zuhd Suyūṭī
abudawud:617 – Aḥmad b. Yūnus > Zuhayr > ʿAbd al-Raḥman b. Ziyād b. Anʿum > ʿAbd al-Raḥman b. Rāfiʿ And Bakr b. Sawādah > ʿAbdullāh b. ʿAmr

The Prophet ﷺ said: When the Imam completes the prayer and sits (for reciting tashahhud), and then becomes defiled (i.e. his ablution becomes void) before he speaks (to someone), his prayer becomes complete. And those who prayed behind him also complete the prayer.  

أبو داود:٦١٧ – حَدَّثَنَا أَحْمَدُ بْنُ يُونُسَ حَدَّثَنَا زُهَيْرٌ حَدَّثَنَا عَبْدُ الرَّحْمَنِ بْنُ زِيَادِ بْنِ أَنْعُمَ عَنْ عَبْدِ الرَّحْمَنِ بْنِ رَافِعٍ وَبَكْرِ بْنِ سَوَادَةَ عَنْ عَبْدِ اللَّهِ بْنِ عَمْرٍو

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ إِذَا قَضَى الإِمَامُ الصَّلاَةَ وَقَعَدَ فَأَحْدَثَ قَبْلَ أَنْ يَتَكَلَّمَ فَقَدْ تَمَّتْ صَلاَتُهُ وَمَنْ كَانَ خَلْفَهُ مِمَّنْ أَتَمَّ الصَّلاَةَ  

See similar narrations below:

Collected by Suyūṭī
suyuti:2361a –

The Prophet ﷺ said: When the Imam completes the prayer and sits (for reciting tashahhud), and then becomes defiled (i.e. his ablution becomes void) before he speaks (to someone), his prayer becomes complete. And those who prayed behind him also complete the prayer. (Using translation from Abū Dāʾūd 617)   

السيوطي:٢٣٦١a –

"إذا قَضى الإِمامُ الصلاةَ وقَعَدَ فأحْدَثَ قبل أنْ يتكلمَّ فقدْ تمت صلاتُه ومَنْ كان خلفَهُ ممّنْ أتمَّ الصلاةَ".  

[د] أبو داود [ن] النسائي وضعفه عن ابن عمرو