Verbiage on Double-Closing Contingency

[David Lee Hall, III]

I have a contract I am selling to a friend that would like to do a double or simultaneous close versus an assignment (could be dry closing, but not required). This is off-market, and he is aware while the home is under contract to me I do not own it. Does anyone have a standard contingency they would be willing to share I could add to my contract given the sale of B (me)->C (him) is dependent on successful closing of A (seller) ->B (me) for legal protection purposes? 

Yes I trust him and yes I would still prefer to include said contingency even though these types of transactions are sometimes viewed as shady. Everything is above the table here, I have just only ever done wholetail with a few weeks between or assignment scenarios.