Hawzah News Agency – Imam al-Askari (AS), when asked about the proof [of Allah] and the Imam after him, said:

ابْنِي محمّدٌ، وهُو الإمامُ والحُجّةُ بَعدي، مَن ماتَ ولَم يَعرفْهُ ماتَ مِيتةً جاهليّةً. أمَا إنّ لَه غَيبةً يَحارُ فيها الجاهلونَ، ويَهْلِكُ فيها المُبطِلونَ، ويَكْذِبُ فيها الوَقّاتونَ، ثُمّ يَخرُجُ فكَأنّي أنظُرُ إلَى الأعْلامِ البِيضِ تَخْفِقُ فوقَ رأسِهِ بِنَجفِ الكوفةِ.

'My son Muhammad will be the Imam and the proof after me. Whoever dies without acknowledging him [as the Imam] has died a death of ignorance. Know that certainly he will have an occultation, about which the ignorant will be left confused, the impugners will be ruined and those who predict a specific time [for his reappearance] will lie. Then he will emerge and it is as if I can see the white flags hovering above his head in Najaf [near] Kufa.'

Source: Bihar al-Anwar, v. 51, p. 160, no. 7