Imam Jaffar (a) says this about love:
He who loves for the sake of Allah is beloved of Allah, and he who is loved for the sake of Allah is also beloved of Allah, since each loves the other for the sake of Allah. The Messenger of Allah said, 'Man is with whom he loves. Whoever loves a bondsman in Allah, loves Allah. No one loves Allah except he whom Allah loves.' And again, 'The best of people after the prophets in this world and the next are those who love each other for Allah.'
Every love based on some cause other than Allah brings about enmity except for these two, for they come from the same source. Theirs always increases and never decreases. As Allah said,
The friends shall on that day be enemies to one another except for those who guard against evil, (
43:67)
because the root of love is being free of everything except the Beloved.
The Commander of the Faithful said, 'The best thing in the Garden and the sweetest is love of Allah, love in Allah, and praise for Allah.' And Allah has said,
The last of their supplication shall be "Praise be to Allah, Lord of the worlds", (
10:10)
because when they see the blessings that exist in the Garden, love is aroused in their hearts and then they call out, 'Praise be to Allah, Lord of the worlds.'
And the previous chapter says:
When love of Allah takes possession of the innermost being of Allah's bondsman, it empties him of every preoccupation except remembrance of Allah. The lover is the most inwardly sincere of all people for Allah. He is the most truthful in his words, the most faithful in his pledge, the most astute in his actions, the purest in remembrance, and the greatest in devoting his self in worship.
The angels compete with each other to converse with him, and boast of having seen him. Through him Allah makes His lands flourish, and by His regard, Allah honours His slaves. Allah gives to people when they ask Him by his right, and removes afflictions from them by His mercy. If people knew how they stand with Allah, they would not try to draw near to Allah save by the dust of his feet.
The Commander of the Faithful said, 'Love of Allah is a fire which does not pass by anything without burning it up; the light of Allah does not come over something without illuminating it.
The skies of Allah do not cause a cloud to appear without it covering whatever is beneath it; the wind of Allah does not blow on something without it moving. Allah's water gives life to everything, and from Allah's earth everything grows. Whoever loves Allah is given every possession and authority.'
The Holy Prophet said, 'When Allah loves a slave in my community, He casts love of him into the hearts of His friends, the spirits of the angels and the keepers of His throne, so that they love him.’
That lover truly has an abundance of bliss, and will be able to intercede with Allah on the Day of Resurrection.'