  More than two decades ago, we studied heavy-flavor-conserving weak decays of
heavy baryons within the framework that incorporates both heavy-quark and
chiral symmetries. In view of the first observation of
$\Xi_b^-\to\Lambda_b^0\pi^-$ by LHCb recently, we have reexamined these decays
and presented updated predictions. The predicted rates for
$\Xi_b^-\to\Lambda_b^0\pi^-$ in the MIT bag and diquark models are consistent
with experiment. The major theoretical uncertainty stems from the evaluation of
baryon matrix elements. The branching fraction of $\Xi_c\to\Lambda_c\pi$ is
predicted to be of order $10^{-4}$. It is suppressed relative to
$Br(\Xi_b\to\Lambda_b\pi)$ owing to the shorter lifetime of $\Xi_c$ relative to
$\Xi_b$ and the destructive nonspectator $W$-exchange contribution. The
kinematically accessible weak decays of the sextet heavy baryon $\Omega_Q$ are
$\Omega_Q\to\Xi_Q\pi$. Due to the absence of the $B_6-B_{\bar 3}$ transition in
the heavy quark limit and the $B_6-B_6$ transition in the model calculations,
$\Omega_Q\to\Xi_Q\pi$ vanish in the heavy quark limit.
