We used to salute the Messenger of Allah ﷺ while he was engaged in prayer and he would respond to our salutation, but when we returned from the Negas, we saluted him and he did not respond to us. He said : Prayer demands one’s whole attention.  

كُنَّا نُسَلِّمُ عَلَى رَسُولِ اللَّهِ ﷺ وَهُوَ فِي الصَّلاَةِ فَيَرُدُّ عَلَيْنَا فَلَمَّا رَجَعْنَا مِنْ عِنْدِ النَّجَاشِيِّ سَلَّمْنَا عَلَيْهِ فَلَمْ يَرُدَّ عَلَيْنَا وَقَالَ إِنَّ فِي الصَّلاَةِ لَشُغْلاً  

We used to salute during prayer and talk about our needs. I came to the Messenger of Allah ﷺ and found him praying. I saluted him, but he did not respond to me. I recalled what happened to me in the past and in the present. When the Messenger of Allah ﷺ finished his prayer, he said to me: Allah, the Almighty, creates new command as He wishes, and Allah, the Exalted, has sent a fresh command that you must not talk during prayer. He then returned my salutation.  

كُنَّا نُسَلِّمُ فِي الصَّلاَةِ وَنَأْمُرُ بِحَاجَتِنَا فَقَدِمْتُ عَلَى رَسُولِ اللَّهِ ﷺ وَهُوَ يُصَلِّي فَسَلَّمْتُ عَلَيْهِ فَلَمْ يَرُدَّ عَلَىَّ السَّلاَمَ فَأَخَذَنِي مَا قَدُمَ وَمَا حَدُثَ فَلَمَّا قَضَى رَسُولُ اللَّهِ ﷺ الصَّلاَةَ قَالَ إِنَّ اللَّهَ يُحْدِثُ مِنْ أَمْرِهِ مَا يَشَاءُ وَإِنَّ اللَّهَ جَلَّ وَعَزَّ قَدْ أَحْدَثَ مِنْ أَمْرِهِ أَنْ لاَ تَكَلَّمُوا فِي الصَّلاَةِ فَرَدَّ عَلَىَّ السَّلاَمَ  

I passed by the Messenger of Allah ﷺ who was praying. I saluted him and he returned it by making a sign. The narrator said: I do not know but that he said: He made a sign with his finger. This is the version reported by Qutaybah.  

أَنَّهُ قَالَ مَرَرْتُ بِرَسُولِ اللَّهِ ﷺ وَهُوَ يُصَلِّي فَسَلَّمْتُ عَلَيْهِ فَرَدَّ إِشَارَةً قَالَ وَلاَ أَعْلَمُهُ إِلاَّ قَالَ إِشَارَةً بِأُصْبُعِهِ وَهَذَا لَفْظُ حَدِيثِ قُتَيْبَةَ  

The prophet of Allah ﷺ sent me to Banu al-Mustaliq. When I returned to him, he was praying on his camel. I talked to him; he made a sign to me with his hand like this. I again talked to him; he made a sign to me with his hand like this. I was hearing him reciting the Qur’an and he was making a sign with his head. When he finished his prayer, he said; what did you do about the mission for which I had sent you; nothing prevented me from talking to you except that I was praying.  

أَرْسَلَنِي نَبِيُّ اللَّهِ ﷺ إِلَى بَنِي الْمُصْطَلِقِ فَأَتَيْتُهُ وَهُوَ يُصَلِّي عَلَى بَعِيرِهِ فَكَلَّمْتُهُ فَقَالَ لِي بِيَدِهِ هَكَذَا ثُمَّ كَلَّمْتُهُ فَقَالَ لِي بِيَدِهِ هَكَذَا وَأَنَا أَسْمَعُهُ يَقْرَأُ وَيُومِئُ بِرَأْسِهِ فَلَمَّا فَرَغَ قَالَ مَا فَعَلْتَ فِي الَّذِي أَرْسَلْتُكَ فَإِنَّهُ لَمْ يَمْنَعْنِي أَنْ أُكَلِّمَكَ إِلاَّ أَنِّي كُنْتُ أُصَلِّي  

The Messenger of Allah ﷺ went to Quba to offer prayer. Then the Ansar (the Helpers) came to him and gave him a salutation while he was engaged in prayer. I asked Bilal: How did you find the Messenger of Allah ﷺ responding to them when they gave him a salutation while he was engaged in prayer. He replied: In this way, and Ja'far ibn Awn demonstrated by spreading his palm, and keeping its inner side below and its back side above.  

سَمِعْتُ عَبْدَ اللَّهِ بْنَ عُمَرَ يَقُولُ خَرَجَ رَسُولُ اللَّهِ ﷺ إِلَى قُبَاءَ يُصَلِّي فِيهِ قَالَ فَجَاءَتْهُ الأَنْصَارُ فَسَلَّمُوا عَلَيْهِ وَهُوَ يُصَلِّي قَالَ فَقُلْتُ لِبِلاَلٍ كَيْفَ رَأَيْتَ رَسُولَ اللَّهِ ﷺ يَرُدُّ عَلَيْهِمْ حِينَ كَانُوا يُسَلِّمُونَ عَلَيْهِ وَهُوَ يُصَلِّي قَالَ يَقُولُ هَكَذَا وَبَسَطَ كَفَّهُ وَبَسَطَ جَعْفَرُ بْنُ عَوْنٍ كَفَّهُ وَجَعَلَ بَطْنَهُ أَسْفَلَ وَجَعَلَ ظَهْرَهُ إِلَى فَوْقٍ  

There is no loss in prayer nor in salutation. Ahmad(b. Hanbal) said: This means, I think, that you do not salute nor you are saluted by others. The loss of a man in his prayer is that a man remains doubtful about it when he finishes it.  

عَنِ النَّبِيِّ ﷺ قَالَ لاَ غِرَارَ فِي صَلاَةٍ وَلاَ تَسْلِيمٍ قَالَ أَحْمَدُ يَعْنِي فِيمَا أُرَى أَنْ لاَ تُسَلِّمَ وَلاَ يُسَلَّمَ عَلَيْكَ وَيُغَرِّرُ الرَّجُلُ بِصَلاَتِهِ فَيَنْصَرِفُ وَهُوَ فِيهَا شَاكٌّ  

There is no loss in salutation and in prayer. Abu Dawud said: According to the version of Ibn Mahdi, this tradition has been narrated by Ibn Fudail as a statement of Abu Hurairah and not as a saying of the Prophet ﷺ  

لاَ غِرَارَ فِي تَسْلِيمٍ وَلاَ صَلاَةٍ