Financing second property

[Account Closed]

I just bought my first property last spring.  It's cash flow positive about $125.  I have about $15k leftover that was also meant to be part rainy day fund part opportunity fund that I didn't expect to touch for a couple years.  I also just took a new job with a 30% paycut (it was worth it).  Then my long time friend and fellow real estate investor (has 3 properties and has been managing two of them for over a decade) approached me about buying a duplex or triplex for about $300k.  Assuming we find a property that we like:

Do I take out a 401k loan for the down payment and keep my rainy day fund liquid for emergencies/market downturns?  Do I pass on the deal now and tell her it's not the right time?

Door number 3?

Thanks in advance.