What is the ruling on ceasing to supplicate for friends with whom this was agreed upon, and does estrangement cease merely by greeting, or by the return of natural conversation?

Fulfilling a promise is, according to the more preponderant opinion, a recommended act. What is more befitting for a Muslim is to be diligent in supplicating for Muslims. The supplication of a Muslim for his Muslim brother in his absence is affirmed by the angels, and they pray for the supplicant in kind, due to the saying of the Messenger of Allah (peace and blessings of Allah be upon him): "The supplication of a Muslim for his brother in his absence is answered. At his head is an angel appointed; whenever he supplicates for his brother with good, the appointed angel says: 'Amin, and to you the like of it.'"