What is the ruling on money I earned from my own private work outside my official working hours in my joint venture with my partner, who does not fulfill his responsibilities in the project, knowing that I do not know its amount?

The partnership is a permissible contract, not a binding one. Each partner has the right to dissolve it or request an increase in their profit share in exchange for increased work. What the questioner did by taking company money for himself without his partner's knowledge is not permissible; it is a betrayal and an unlawful appropriation of wealth. He must repent, seek forgiveness, and seek his partner's absolution by returning the right he took from him. If he is unaware of the amount, he should strive to estimate it until he is reasonably certain that he has fully repaid his partner's right.