Kitāb al-Ghayba

Hadith 690
occultation
422- الفضل بن شاذان، عن محمد بن علي، عن سعدان بن مسلم، عن أبي بصير قال:قلت له: ألهذا الامر أمد نريح أبداننا وننتهي إليه؟ قال: بلى ولكنكم أذعتم فزاد الله فيه.
H 422 - Fadhl bin Shazan has narrated from Muhammad bin Ali from Sadan bin Muslim from Abu Basir that he said: I asked Imam Muhammad Baqir (a.s) or Imam Ja’far Sadiq (a.s): “Does reappearance of the master of affair has a fixed time that we might rest assured be pleased with it?” He replied: “Yes, it was fixed, but you people divulged it and Almighty Allah postponed it.”
Source: Shaykh Muḥammad b. al-Ḥasan al-Ṭūsī