Hawzah News Agency - Muhammad ibn ‘Isma’il has narrated from al-Fadl ibn Shadhan from Hammad ibn ‘Isa from Ri’ab‘i ibn ‘Abdallah from Muhammad ibn Muslim from abu ‘Abdallah who has said the following.

لِلْعَالِمِ إِذَا سُئِلَ عَنْ شَيْ‏ءٍ وَهُوَ لا يَعْلَمُهُ أَنْ يَقُولَ الله أَعْلَمُ وَلَيْسَ لِغَيْرِ الْعَالِمِ أَنْ يَقُولَ ذَلِكَ.

“It is very proper for a scholar to say, ‘Allah knows best’ if he does not know. This is not for a none scholar.”

Al-Kāfi, v.1, Book 2, Chapter 11