Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
Which date did the oakland raiders play as the opponent when the Bills first downs were under 28?

### Inputs:
table_name: table, columns: ['Game', 'Date', 'Opponent', 'Result', 'Bills points', 'Opponents', 'Bills first downs', 'Record', 'Attendance']

### Response:
SELECT Date FROM table WHERE Bills first downs < 28 AND Opponent = oakland raiders