Do I need a bank statement or my income statement for just 3 days in china

I want to go to China to attend a friend graduation for 3 days do I need a letter of authorization from my manager cause it will be on a weekend(graduation) and Monday I will report to work. Also do I need a bank statement or my income statement?
To mention I have been working 3 months ago should the statement of incomes be 6 months still? Mine is just 3 month and I wanna go for a 3 days graduation. Thanks for answering