A man came to the Abbaside king Mansur Dawaniqi and began to instigate him against Imam Ja’far as-Sadiq (a.s.). He said, “He desires to launch an attack upon you. He has sent money to different places for this and continues to do so. He has always supported the sons of Abdullah Ibn Hasan, Muhammad and Ibrahīm, and these two have confronted you.”
Mansur summoned Imam Ja’far as-Sadiq (a.s.) from Madinah. When Imam (a.s.) reached the court of Mansur, he quoted the false allegations and severely criticised the Imam (a.s.).
Imam (a.s.) replied,
“I seek the refuge of Allah from such things. All these are false allegations.”
Mansur called the man who had laid these false allegations against Imam (a.s.). The accused man came and repeated his accusations. Imam as-Sadiq (a.s.) asked him,
“Can you swear for the truth of your statements?”
This accused person began to say, “By Allah! The one besides whom there is no god, He is the…”
Imam (a.s.) interrupted him,
“Do not make haste in taking the oath, say as I command you.”
Mansur asked, “Is there any defect in the oath which he has taken?”
Imam replied,
“When a man swears by Allah, praising the Divine qualities, Allah refrains from sending an immediate retribution. So he should say like this, ‘I swear by Allah ignoring His Might and Power and seek the refuge on my own might and power that whatever I have said is the truth.’”
Mansur ordered that man to swear in this manner. The man began to take the oath and had not even completed it when his tongue rolled out like a dog and he fell down dead.