This seems like a ideal opportunity to see how well you and your partner will be able to handle the `differences of opinion` that will arise in any and all partnerships. I would hope that you can both express your reasons for each of your postions, and then come to some agreement. You might want to establish a phased in approach - continue working for x period of time, and then stick to the agreed timeframe. The key point I would think is that if this is going to be a major issue that can`t be worked out, a partnership might not be the best approach for you two.
You didn`t mention a reason for wanting to continue working. I do know that trying to continue working a job can get in the way of running a full time business. Several years ago, I chose to walk away from my job to start up a business, specifically because I knew that I would be shortchanging both my employer and my business by trying to split my time. But if your concern is that you don`t have enough startup money available to keep food on the table during the startup phase, then you might need to hold on to the job. I had what I believed were sufficient funds to get me through the startup, but I learned the hard way that building the business can be slower than you expect. Since I already walked away from the job I was limited in my options for additional funds. If funding is a concern, be careful that you have a realistic (make that conservative) business plan, and make sure that you will be able to keep food on the table. If that can be done in some manner without the job, your business would probably be better served with you both focusing on it full time.
When life gives you lemons, share the lemonade!