That he/she shall keep himself/herself occupied in the service of God’s creatures for His sake only and shall endeavour towards the beneficence of mankind to the best of his/her God-given abilities and powers.
Allah the Almighty says in the Holy Qur’an:1
And worship Allah and associate naught with Him, and show kindness to parents, and to kindred, and orphans, and the needy, and to the neighbour that is a kinsman and the neighbour that is a stranger, and the companion by your side, and the wayfarer, and those whom your right hands possess. Surely, Allah loves not the proud and the boastful.
1 al-Nisa’, 4:37