What is from the minor jihad to the major? What is minor jihad?
Tabuk, the final military campaign which the Blessed Prophet -upon him blessings and peace- personally led, was a campaign of hardships. The Muslim army had crossed a distance of a thousand kilometers just to reach Tabuk and had covered the same distance to return. With dust covering their unkempt hairs and beards, the Companions had virtually been reduced to skin and bone. Still, the Blessed Prophet -upon him blessings and peace- told them, “We are now returning from the minor jihad to the major!”
The Companions were astounded. “Look at us, Messenger of Allah. Could there ever be a greater jihad than this?” they wondered.
“We are now returning to the major jihad”, repeated the Blessed Prophet -upon him blessings and peace-, “the jihad against the nafs (ego).” (Suyuti, II, 73)
The jihad against the ego is the spiritual training of the heart, carrying the aim of refining one spiritually, by virtue of elevating his moral conduct, and turning the person into a perfect human being (insan-i kamil). The way leading to this lies in a reason enmeshed in Divine truths, a heart adorned with iman and beautiful morals, an overall state crowned with the spirituality of the Quran and Sunnah, and perfection through reaching the ascension of tawhid by virtue of upright behavior.
The entire Muslims in Medina, young and old, flocked to Saniyyat’ul-Wada to welcome the Blessed Prophet -upon him blessings and peace- and the Companions as they made a triumphant return to Medina.
 Bukhari, Jihad, 196.