-ksh: pushd: not found

I am new to Unix and I am trying to used pushd, popd and dirs in SUSE Linux but I am getting

-ksh: pushd: not found 

while I try to check pushd

 which pushd
which: no pushd in (/usr/bin:/bin:/usr/sbin:/sbin)

I am getting there is not pushd. How to solve this issued.