What is the ruling on signing a pledge not to participate in political organizations or religious proselytization in exchange for continuing one's studies in a foreign country?

There is no harm in signing that, if a Muslim needs it for a clear benefit. Indeed, acting upon Islam is not limited to participating in political organizations or religious groups. Rather, it is sufficient for a Muslim to learn Islam, act upon it, and invite others to it with wisdom and good counsel, so that success in both worlds may be achieved for him, as Allah Almighty said: "By the Aṣr (Time). Indeed, mankind is in loss, Except for those who have believed and done righteous deeds and advised each other to truth and advised each other to patience."