user: Question: On what date was Motherwell the opponent at Fir Park?
Columns: ['Date', 'Round', 'Opponent', 'Venue', 'Result', 'Attendance']
Types: ['text', 'text', 'text', 'text', 'text', 'real']
Sample row: ['13/01/2009', 'R4', 'Brechin City', 'Glebe Park', '3–1', 1026.0]
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Opponent" = 'Motherwell' AND "Venue" = 'Fir Park';