When must a Muslim correct a wrong immediately, advise privately, delay for a greater benefit, or leave the gathering? When does fear of alienating someone justify postponing correction, and when is silence blameworthy?

Correct it when you can, and choose the right moments with gentleness and wisdom. If correcting it would lead to a greater evil, leave it, and you may wait for the right moment, then remind him when you are alone with him. Staying silent out of courtesy is incorrect, so correct what is wrong and advise when there is use and it does not lead to greater evil.