Al-Matalib al-'Aliyah 3181 — Permissibility of guarding oneself

It is narrated from Ubaydullah bin al-Ayzar that he met an aged Bedouin man in a sandy region and asked him: Have you met any of the Companions of the Messenger of Allah (peace and blessings be upon him)? He replied: Yes. I asked: Who was that elder? He said: It was Sayyiduna Abdullah bin Amr bin al-As (may Allah be pleased with them both). I said to him: What did you hear him say? He said: I heard Sayyiduna Abdullah bin Amr (may Allah be pleased with them both) saying: "Strive for the betterment of your worldly life as though you are to live in this world forever, and work for the success of your Hereafter as though you will meet death tomorrow."
Al-Harith bin Abi Usamah mentioned this report in his Musnad, and this saying of Sayyiduna Abdullah bin Amr bin al-As (may Allah be pleased with them both) expresses a perfect balance between two important aspects of life, namely building the world and preparing for the Hereafter, and an insightful Prophetic approach.