The Messenger of Allah ﷺ sent a man on a campaign, and he used to recite to his companions when leading them in prayer, and would conclude with 'Say: He is Allah, (the) One.' When they returned, they told the Messenger of Allah ﷺ about that. He said: "Ask them why he did that." So they asked him and he said: "Because it is a description of the Most Merciful, the Mighty and Sublime, and I love to recite it." The Messenger of Allah ﷺ said: "Tell him that Allah (SWT), the Mighty and Sublime, loves him."
أَنَّ رَسُولَ اللَّهِ ﷺ بَعَثَ رَجُلاً عَلَى سَرِيَّةٍ فَكَانَ يَقْرَأُ لأَصْحَابِهِ فِي صَلاَتِهِمْ فَيَخْتِمُ بِ { قُلْ هُوَ اللَّهُ أَحَدٌ } فَلَمَّا رَجَعُوا ذَكَرُوا ذَلِكَ لِرَسُولِ اللَّهِ ﷺ فَقَالَ سَلُوهُ لأَىِّ شَىْءٍ فَعَلَ ذَلِكَ فَسَأَلُوهُ فَقَالَ لأَنَّهَا صِفَةُ الرَّحْمَنِ ﷻ فَأَنَا أُحِبُّ أَنْ أَقْرَأَ بِهَا قَالَ رَسُولُ اللَّهِ ﷺ أَخْبِرُوهُ أَنَّ اللَّهَ ﷻ يُحِبُّهُ