I know a brother in Islam, who left his haram (impermissible) job, after realising the haram nature of it - Alhamdu Lillah.
He is now looking for a job that is just sufficient to feed and clothe his family. He is keen to work only as many days to earn that income. The rest of the week he wants to spend in the mosque reading the Quran and praying, etc.
Is his behaviour permissible? Does Islam not say that the daytime is for seeking sustenance and the night for prayers? Is it not better for him to seek a good job so that the extra money can be given as zakah (alms) to the poor? Doesn't his family have rights over him with regard to time?
The Muslim who is able to earn a living must strive to earn that which will keep him and those under his guardianship, such as his wife and children, from having to beg, and to earn what he needs to spend on their maintenance. If he manages to do this, then if he spends the rest of his time, whether during the night or the day, in worshipping Allah by praying, fasting, reading the Quran, then that is better. There is no specific time for worship in general, but yes, praying qiyam (voluntary prayers) at night is better than praying during the day. This does not mean that there is no reward for praying nafil (extra) prayers during the day. He should start by doing that which is obligatory, whether the obligation is towards Allah or towards His creation, then he can use the rest of his time for doing that which is mustahabb (encouraged), and if he indulges in some permissible activities for the purpose of relaxation and recreation, that is OK.
And Allah knows best.