Love and brotherhood

It is narrated from Sayyiduna Ali (may Allah be pleased with him) that he said: "Be moderate and balanced in loving your beloved and friend, for it is quite possible that one day he becomes your enemy and someone you dislike; and likewise, do not exceed limits in hating your enemy, but keep balance and gentleness, for it may be that one day he becomes your beloved and close friend."
Imam al-Tirmidhi recorded this hadith in his Sunan (1997), and Allamah al-Albani declared it sahih (authentic).

It is narrated from Imam al-Hasan al-Basri (may Allah have mercy on him) that he said: "Whenever a Muslim increases his bond of religious brotherhood and Islamic fraternity for the pleasure and good will of Allah Almighty, Allah, the Lord of Might, raises his ranks of faith and his stations in the Hereafter by virtue of this deed."
[Takhrij: This narration is a saying (athar) of Imam al-Hasan al-Basri (may Allah have mercy on him), which Mu'tamir bin Sulayman transmitted through Humayd al-Tawil, and its chain is sahih (authentic)].

It is narrated from Amr bin Maymun (may Allah have mercy on him) that the Messenger of Allah (peace and blessings be upon him) said: "When one of you loves a person (a servant of Allah), let him inform him of it, for that other person will certainly find in his heart the same feelings and love for him as this one feels for him."
This narration is mursal.

It is narrated from Mujahid (may Allah have mercy on him) that a man passed by Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both), and he said (pointing towards him): "Indeed, this man loves me." The people said: O Ibn Abbas! How did you come to know this? He said: "Because I love him (and hearts are connected to hearts)."
Imam Abu Ya'la (may Allah have mercy on him) recorded this hadith in his Musnad.

It is narrated from Sayyiduna Anas (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever takes someone as his brother for the sake of Islam, Allah Almighty raises him by one degree in Paradise because of it. And whenever two servants love one another for the pleasure of Allah Almighty and then separation occurs between them, it is only because of a sin committed by one of them. And whenever two servants hold mutual affection and love purely for the pleasure of Allah Almighty, the more virtuous of them with Allah, the Mighty and Majestic, is the one who loves his companion more intensely."
Imam al-Bayhaqi recorded it in his book 'Shu'ab al-Iman'. The imams of narrator criticism have criticised the narrator in its chain, Abu Isma'il al-Abdi (Bishr bin Hudhayfah); however, supporting narrations for this hadith concerning the virtues of love for the sake of Allah are found in other reliable reports.

It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "Those who love one another for the pleasure of Allah will be (on the Day of Resurrection) seated upon a lofty pillar of red ruby, from where they will be visible over the people of the world." He (peace and blessings be upon him) said: "At that time the people of Paradise will say (with great eagerness): Come with us so that we may look at those who used to love one another for the sake of Allah, the Mighty and Majestic." He (peace and blessings be upon him) said: "So they will go out (to visit them) and look at them; their faces will be shining like the moon on the night of the full moon, and on their foreheads it will be inscribed: These are the ones who used to love one another for the sake of Allah, the Mighty and Majestic."
In the narration of Imam Abu Ya'la there is this addition: "At the top of that pillar there will be seventy thousand upper chambers; their beauty will shine upon the people of Paradise just as the sun spreads light upon the people of the world." And it is also mentioned in this narration that they will be wearing green garments of fine silk.

It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Indeed, in Paradise there are lofty pillars of ruby upon which are upper chambers made of chrysolite (zabarjad); their doors are open, and they shine just as a bright, brilliant star shines." We said: O Messenger of Allah! Who will dwell in them? He (peace and blessings be upon him) said: "In them will live those who love one another for the pleasure of Allah, the Mighty and Majestic, who sit in one another's company for the sake of Allah Almighty, and who hold mutual affection and harmony for the pleasure of Allah, Majestic is His Majesty."
In the chain of this hadith, the narrator named Hammad bin Abi Humayd is weak; however, its meaning is supported by other hadith. (Musnad Abd bin Humayd: 1421).

It is narrated from Sayyiduna Anas (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Never have two persons loved one another but that the more virtuous and superior of the two in the sight of Allah is the one who has the more intense and deeper love for his companion."
Imam Abu Ya'la recorded this hadith in his Musnad, and Allamah al-Albani (may Allah have mercy on him) declared it sahih (authentic) in 'Sahih al-Jami' al-Saghir' (hadith: 5594) and 'Silsilat al-Ahadith al-Sahihah' (hadith: 450).