How can one balance the demands of this world and the Hereafter, and is abandoning worldly ambitions for the sake of the Hereafter considered selling this world?

The balance between striving for worldly gains and working for the Hereafter is achieved by moderation in worldly pursuits without neglecting religious obligations, while making the Hereafter the greatest concern. For whoever has the Hereafter as their primary concern, Allah will gather their affairs and the world will come to them willingly. But whoever has the world as their primary concern, Allah will scatter their affairs and they will not receive from it except what has been decreed for them.

There is no blame in striving to obtain worldly benefits. The Quran has permitted seeking Allah's bounty and has highlighted various legitimate forms of trade. The Prophet, peace be upon him, considered striving to earn a livelihood for one's family or oneself as an act of modesty akin to striving in the path of Allah.

A wise person should not neglect four hours: an hour for supplicating their Lord, an hour for self-reckoning, an hour for their sincere brethren, and an hour for lawful pleasure that aids in the other hours. They must also be aware of their time, control their tongue, attend to their own affairs, and be engaged in one of three things: provision for the Hereafter, determination for a livelihood, or lawful enjoyment.