'Umar bin Khattab (may Allah be pleased with him) narrates that it was said: "O Messenger of Allah! So-and-so man has been martyred." He replied: "Never! I saw him in the Hellfire because of the cloak (garment) which he had stolen from the spoils of war." He (the Prophet) said: "Umar! Stand up and announce three times that only believers will enter Paradise." (And a believer does not commit treachery.)
It is reported on the authority of Ta'us that a man said to 'Abdullah son of 'Umar (RA) . Why don't you carry out a military expedition? Upon which he replied: I heard the messenger of Allah (ﷺ) say: Verily, al-Islam is founded on five (pillars): testifying the fact that there is no god but Allah, establishment of prayer, payment of Zakat, fast of Ramadan and Pilgrimage to the House.
Shaykh Maulana Abdul Aziz Alvi
Hadith Commentary:
Benefits and Issues: ➊ The person who asked Abdullah ibn Umar radi Allahu anhuma was a man named Hakim. ➋ Jihad, unlike the five pillars of Islam, is not inherently intended or required in itself, but like other matters of Islam, it becomes obligatory (fard) only in certain temporary (necessary and needed) circumstances, specific conditions, and particular occasions. Therefore, jihad is not obligatory at all times, in every situation, nor upon every man and woman, and for this reason, jihad has not been included among the pillars of Islam.
Source: Tuhfat al-Muslim: Commentary on Sahih Muslim, Page: 114