“Many a brother is one your mother never bore.”

A classical Arabic proverb that Ibn ‘Abd Rabbih gives as a saying of the sages in al-‘Iqd al-Farid. Ibn Sa‘d records al-Hasan al-Basri saying it when a letter from ‘Abd al-Malik ibn Abi Bashir was read to him and turned out to contain a supplication for him — just after noting that al-Hasan disliked being praised to his face but was glad to be prayed for. Brotherhood in faith is a real bond in Islam, with rights attached, not a figure of speech.