Understanding Usul Al-Fiqh by Abu Tariq Hilal - Abu Ismael al-Beirawi

The Sahabah (ra) used to make Ijtihad in the time of the Messenger of Allah (saw) and differ in their deduction of Ahkams and the Messenger (saw) accepted this. This can be seen in the following incidents:

1) Bukhari narrated from Aisha that when the Prophet (saw) returned from the battle of Khandaq (ditch) and laid down his arms and took a bath. Jibreel came and said, “You have laid down your arms? By Allah, we angels have not laid them down yet. So set out for them.” The Messenger (saw) asked, “where to go?” so Jibreel pointed towards Banu Qurayzah. The Prophet (saw) instructed the Mu`azzin to give Azan and so he announced to the people:

“Whosoever believes in Allah and the Day of judgement he should not pray Asr except in Bani Qurayzah.” So thy headed towards the fortresses of Bani Qurayzah, however they had different understandings of what the Messenger (saw) had said to them. Some took the literal meaning and they did not pray until they reached Bani Qurayzah after Maghrib. And others took it to mean that they should go there quickly, so they prayed Asr in Madinah or on the way. When the Messenger (saw) heard about this he accepted the action of all them.32

2) The saying of the Prophet (saw) when he sent Mu‟adh as Qadi to Yemen:

“By what will you pass judgement?‟ He said: By the Book of Allah. The Prophet (saw) said: If you do not find it there? He said: By the Sunnah of the Messenger of Allah (saw). He said: And if you do not find it? He said: 'I will exercise my own Ijtihad‟. He (saw) said:

“Praise be to Allah who has made the messenger of the Messenger of Allah to accord with what Allah and His Messenger loves.”33

3) The Hadith of the Messenger (saw):

“If a judge passes judgment and makes Ijtihad and he is right then he will have two rewards. And if he makes a mistake he will have one.”34

4) The Messenger of Allah (saw) made Sa‟d b. Mu‟adh to judge over Bani Qurayzah so he gave the judgment that they should be killed and their offspring to be taken prisoners. The Messenger (saw) said:

“You have given a judgment that is from above the seven heavens.”35

From these examples we can see that the Sahabah used to make Ijtihad in the time of the Messenger (saw) and that he used to accept their Ijtihads and tell them that the one who got it right will get two rewards while the one who got it wrong will get one.