We used to greet the Prophet ﷺ while he was praying and he used to answer our greetings. When we returned from An-Najashi (the ruler of Ethiopia), we greeted him, but he did not answer us (during the prayer) and (after finishing the prayer) he said, "In the prayer one is occupied (with a more serious matter)."  

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

We used to greet the Messenger of Allah ﷺ while he was engaged in prayer and he would respond to our greeting. But when we returned from the Negus we greeted him and he did not respond to us; so we said: Messenger of Allah. we used to greet you when you were engaged in prayer and you would respond to us. He replied: Prayer demands whole attention.  

كُنَّا نُسَلِّمُ عَلَى رَسُولِ اللَّهِ ﷺ وَهُوَ فِي الصَّلاَةِ فَيَرُدُّ عَلَيْنَا فَلَمَّا رَجَعْنَا مِنْ عِنْدِ النَّجَاشِي سَلَّمْنَا عَلَيْهِ فَلَمْ يَرُدَّ عَلَيْنَا فَقُلْنَا يَا رَسُولَ اللَّهِ كُنَّا نُسَلِّمُ عَلَيْكَ فِي الصَّلاَةِ فَتَرُدُّ عَلَيْنَا فَقَالَ إِنَّ فِي الصَّلاَةِ شُغُلاً  

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 greet the Messenger of Allah ﷺ while he was engaged in prayer and he would respond to our greeting. But when we returned from the Negus we greeted him and he did not respond to us; so we said: Messenger of Allah. we used to greet you when you were engaged in prayer and you would respond to us. He replied: Prayer demands whole attention. (Using translation from Muslim 538a)  

كُنَّا نُسَلِّمُ عَلَى رَسُولِ اللهِ ﷺ وَهُوَ فِي الصَّلَاةِ فَيَرُدُّ عَلَيْنَا فَلَمَّا رَجَعْنَا مِنْ عِنْدِ النَّجَاشِيِّ سَلَّمْنَا عَلَيْهِ فَلَمْ يَرُدَّ عَلَيْنَا فَقُلْنَا يَا رَسُولَ اللهِ كُنَّا نُسَلِّمُ عَلَيْكَ فِي الصَّلَاةِفَتَرُدُّ عَلَيْنَا؟ فَقَالَ إِنَّ فِيَّ أَوْ فِي الصَّلَاةِ لَشُغْلًا  

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. (Using translation from Abū Dāʾūd 923)   

عَبْدُ اللهِ كُنَّا نُسَلِّمُ عَلَى النَّبِيِّ ﷺ فِي الصَّلَاةِ حَتَّى رَجَعْنَا مِنْ عِنْدِ النَّجَاشِيِّ فَسَلَّمْنَا عَلَيْهِ فَلَمْ يَرُدَّ عَلَيْنَا وَقَالَ إِنَّ فِي الصَّلَاةِ شُغْلًا  

We used to greet the Messenger of Allah ﷺ while he was engaged in prayer and he would respond to our greeting. But when we returned from the Negus we greeted him and he did not respond to us; so we said: Messenger of Allah. we used to greet you when you were engaged in prayer and you would respond to us. He replied: Prayer demands whole attention. (Using translation from Muslim 538a)  

كُنَّا نُسَلِّمُ عَلَى رَسُولِ اللهِ ﷺ وَهُوَ فِي الصَّلَاةِ فَيَرُدَّ عَلَيْنَا فَلَمَّا رَجَعْنَا مِنْ عِنْدِ النَّجَاشِيِّ سَلَّمْنَا عَلَيْهِ فَلَمْ يَرُدَّ عَلَيْنَا فَقُلْنَا يَا رَسُولَ اللهِ كُنَّا نُسَلِّمُ عَلَيْكَ فِي الصَّلَاةِ فَتُرَدَّ عَلَيْنَا قَالَ «إِنَّ فِي الصَّلَاةِ شُغْلًا»  

[Machine] We used to greet the Messenger of Allah ﷺ while he was praying, and he would respond to us. But when we arrived in Habasha (Ethiopia) and returned, we greeted him and he did not respond. So we asked him, and he said, "Indeed, I was preoccupied in prayer."  

كُنَّا نُسَلِّمُ عَلَى رَسُولِ اللهِ ﷺ وَهُوَ يُصَلِّي فَيَرُدُّ عَلَيْنَا فَلَمَّا أَتَيْنَا الْحَبَشَ فَرَجَعْنَا فَسَلَّمْنَا عَلَيْهِ فَلَمْ يُرِدَّ فَسَأَلْنَاهُ فَقَالَ «إِنَّ فِي الصَّلَاةِ شُغْلًا»