مُعْتَرِفِينَ ... مُصَدِّقِينَ
Those who acknowledge and affirm.
Acknowledgement professes the Messenger's mission and the religion he brought. Affirmation accepts as true reports reliably established from him. Faith is therefore not merely a label or custom but conviction concerning revelation.
A report must genuinely be established from the Messenger before it is treated as his teaching; mere attribution is not sufficient.