4 Answers

In Canada this is not legal.  If you are paid monthly then you should receive your full pay cheque at the end of each month within a very short period of time after the pay period ends.  A very short time.

Contact the labour relations board in your country or go on line.  All this information is available to you as a citizen of the country you live in excepting a few.

Where is it that you work? What country? 

In the states your boss would have been put through a wall, then dragged into court.

Ask them (better still, tell them) that you will take a 4-week paid sabbatical and will make it up to them AFTER they pay you for the 4 weeks owing. I'm sure that they'll understand their very own line of thinking.