The Prophet ﷺ said, "When one of you loves his brother, let him tell him so, for he will find in him the same feeling he has toward him."
عن النبي ﷺ قال: إذا أحب أحدكم أخاه فليعلمه فإنه يجد له مثل الذي يجد عنده.
Ibn Abu Dunya narrated it in al-Ikhwan (74), and Bayhaqi in al-Shuab (8595), both through the route of Abdullah bin Abdul-Wahhab al-Hajabi, who said, Abu Awana narrated to us, from Mansur (that is, Ibn al-Mutamir), from Abdullah bin Mura (that is, al-Hamdani), from Abdullah bin Umar, and he mentioned it. Its chain is sahih.It has also been narrated from Ali bin Husayn, who said, the Messenger of Allah ﷺ said, "When one of you loves his brother for the sake of Allah, let him inform him of it, for that is better for fostering closeness and more lasting for affection." Waki narrated it in al-Zuhd (337), from Masaar, from Amr bin Mura, from Ali bin Husayn, and he mentioned it. Its narrators are trustworthy, except that it is mursal, for Ali bin Husayn bin Ali bin Abu Talib, who is Zayn al-Abidin, is a trustworthy and eminent Tabi'i, and his hadith is mursal.In a similar meaning, it has also been narrated from Mujahid, who said, I was told that the Prophet ﷺ said, "When one of you loves his brother for the sake of Allah, let him let him know it, for that is more lasting for closeness and firmer for affection." Ibn Abu Dunya narrated it in al-Ikhwan (69) with his chain, and its narrators are trustworthy, except that it is munqati.