Well, Allah detests their setting out more than you do, and...
Alternative Sources for Sermon 146 (1) Al-Dinawari, al-'Akhbar, 134; (2) Ibn A`tham, al-Futuh, II, 37; (3) al-Tabari, Ta'rikh, IV, 237 events of 27 H.; (4) al-Mufid, al-'Irshad, 120; (5) Ibn Miskawayh, Tajarib, I, 419.
[^1]: When some people advised Caliph `Umar to partake in the battle of al-Qadisiyyah or Nahawand, he finding it against his personal inclination, thought it necessary to consult Amir al-mu'minin, so that if he advised against it he would plead before others that he had stayed back on Amir al-mu'minin's advice, but also if he advised partaking in the battle some other excuse would be found. However, unlike others, Amir al-mu'minin advised him to stay back.
The other people had advised him to join in fighting, because the Holy Prophet did not send only others to fight but took part in it himself as well, keeping his close relations also with him. What Amir al-mu'minin had in view was that `Umar's presence in the battle could not be beneficial to Islam, but rather his staying back would save the Muslims from dispersion.
Amir al-mu'minin's view that "the position of the head of government is that of the axis around which the system of the government rotates" is a point of principle and does not concern any particular personality. Whether the ruler is a Muslim or an unbeliever, just or despotic, virtuous or vicious, for the administration of the state his presence is a necessity, as Amir al-mu'minin has explained elsewhere at greater length: The fact is that there is no escape for men from a ruler good or bad.
Faithful persons perform (good) acts in his rule while the unfaithful enjoys (worldly) benefits in it.