This is from John Greig's Scots Minstrelsie 1895, Vol Vl, notes xxxiii:

Sae Will We Yet, (p. 375). In a concert programme "Sae Will We Yet" is a song to conjure with. It was one of the battle-horses of that great Scottish vocalist the late Mr David Kennedy; it is sure of "bringing down the house" when Mr James Lumsden "buckles to it"; while Mr Robert Kennedy, the successor to his father, has again brought it to the front. The air is a variation of the characteristic Irish melody "The Wearin' o' the Green," and is confined to the notes of the pentatonic scale. "Laugh and be Thankful," of which "Say Will We Yet" is a refined version, was published in "Whistle Binkie" (1832-1853). To the same may be also sung that favourite convivial effusion entitled "A Wee Drappie o't," which we have appended:- .....................

There are no credits but we've gone into this before and Jim Carroll has confirmed who wrote it (see above).