I have 2 spreadsheets

The first is a large table with thousands of invoice numbers in no
particular order that have been billed.

Weekly I get a second spreadsheet with a set of 50 or so invoice numbers
that appear somewhere on the first sheet (no particular order). These are
invoices that have been paid that week. This sheet also shows the date paid.

I need a formula to match the invoice numbers from the paid sheet to the
billed sheet and return the date paid in another column on that billed sheet