How are shares distributed among four partners in a company, where the first is an investor, the second procures projects, and the third and fourth are executors (with variation in the frequency of execution), according to the Quran and Sunnah?

The partnership between you is called a Mudarabah (definition), where capital comes from one party and effort from another. The profit is distributed according to an agreed-upon, known percentage, such as half or a quarter, not a fixed amount or a percentage of the capital. The distribution percentage must be agreed upon at the time of contracting and can be changed by mutual consent of both parties. If the parties do not agree, reference is made to custom. If no custom exists, the Mudarabah becomes invalid, and the Mudarib receives a fair wage (ajr al-mithl). If there is no agreement, reference is made to the custom in similar partnerships. If no custom exists, the partnership becomes null and void, and the partners are entitled to a fair wage (ajr al-mithl) for their work.