The Prophet (peace and blessings be upon him) said:
"You are our brother and our mawla (freed slave and friend)." (He (peace and blessings be upon him) said this to Sayyiduna Zayd bin Harithah (may Allah be pleased with him).)
Hadith Referenceصحیح الجامع الصغیر / حرف الألف / 1479