You don't specify the distribution, but I assume you want normally distributed values from N(3,1)? Here is a PROC IML solution:
proc iml;
x = j(20, 30); /* allocate 20x30 matrix */
call randseed(123); /* seed random seed */
call randgen(x, "Normal", 3, 1); /* N(3,1) */
For more about generating random samples, see http://blogs.sas.com/content/iml/2010/09/22/efficient-sampling/
If you one day want a sample from a multivariate normal distribution, see http://blogs.sas.com/content/iml/2011/01/12/sampling-from-the-multivariate-normal-distribution/