红薯说的对，在商言商，你可以论法不论情。但我会至少给别人一个月时间，并写一封信给他

地主应该有空房期预算，人家四年按时付租意味着你四年满租，因此就算你给他一个月credit也不为过。

无果是我，我会给他发个短信：

My friend；I am so sorry to hear that you lost your job.I understand that everybody has temporarily difficult. I hope you will find a new job in short future. I believe you will do your best. Since you have lived in my house over 4 years without any troble, I decide to give you one month credit. I treasure our friendship. However, after that I will increase my rent to $????. You know both property tax and insurance have markedly increased in this 4 years.

我想如果他找到新工作，他会欣然接受新的租金并签新约，因此，你不一定有损失，如果他再住几年你或许还挣更多。但你收获了一份友谊。你们或许会传下一段佳话。如果他找不到工作，我想他会自己离开。