I asked Abu Wail, "Did you take part in the battle of Siffin?" He said, 'Yes, and I heard Sahl bin Hunaif (when he was blamed for lack of zeal for fighting) saying, "You'd better blame your wrong opinions. I wish you had seen me on the day of Abu Jandal. If I had the courage to disobey the Prophet's orders, I would have done so. We had kept out swords on our necks and shoulders, for a thing which frightened us. And we did so, we found it easier for us, except in the case of the above battle (of ours).' "  

أَنْ أَرُدَّ أَمْرَ النَّبِيِّ ﷺ لَرَدَدْتُهُ وَمَا وَضَعْنَا أَسْيَافَنَا عَلَى عَوَاتِقِنَا لأَمْرٍ يُفْظِعُنَا إِلاَّ أَسْهَلْنَ بِنَا إِلَى أَمْرٍ نَعْرِفُهُ غَيْرِ أَمْرِنَا هَذَا  

I heard Sahl b. Hunaif say at Siffin: O ye people, find fault with your (own) discretion. By Allah, on the Day of Abu Jandal (i. e. the day of Hudaibiya), I thought to myself that, if I could, I would reverse the order of the Messenger of Allah ﷺ (the terms of the truce being unpalatable). By Allah, we have never hung our swords on our shoulders in any situation whatsoever except when they made easy for us to realise the goal envisaged by us, but this battle of yours (seems to be an exception). Ibn Numair (in his version) did not mention the words:" In any situation whatsoever" (Using translation from Muslim 1785b)   

أَنْ أَرُدَّ أَمْرَ رَسُولِ اللهِ ﷺ لَرَدَدْتُهُ وَاللهِ مَا وَضَعْنَا سُيُوفَنَا عَلَى عَوَاتِقِنَا إِلَى أَمْرٍ قَطُّ إِلَّا أَسْهَلَ بِنَا إِلَى أَمْرٍ نَعْرِفُهُ إِلَّا أَمْرَكُمْ هَذَا»  

"عَنْ شَفِيقٍ أَبِى وَائِلٍ قَالَ: سَمِعْتُ سَهْلَ بْنَ حُنَيْفٍ يَقُولُ بِصِفَّينَ: أَيُّهَا النَّاسُ اتَّهِمُوا رَأيَكُمْ، فَوَالله لَقَدْ رَأَيْتُنِى يَوْمَ أَبِى جَنْدَلٍ وَلَوْ أَسْتَطِيعُ أَنْ أَرُدَّ أَمْرَ رَسُولِ الله ﷺ لَرَدَدْتُهُ، وَالله مَا وَضَعْنَا سُيُوفَنَا عَلَى عَوَاتِقِنَا مَعَ رَسُولِ الله ﷺ لأَمْرٍ يُقْطِعُنَا قَطُّ إِلاَّ أَسْهَلَ بِنَا إِلاَّ (*) أَمْر نَعْرِفُهُ إِلاَّ أَمْركُمْ هَذَا".