Justifications are a very useful tool for explaining DL consequences. They highlight parts of the ontology that are responsible for the consequence, and can serve as the basis for more detailed explanations such as proofs. In this paper, we present an approach that can compute ABox justifications, ie justifications restricted to assertions, for answers to conjunctive queries, assuming that these queries are Datalog-rewritable over the input ontology. We implemented the approach based on the rewriting tool Clipper and ProvSQL, which can be used to compute provenance information, including justifications, for SQL queries. The potentially recursive nature of Datalog rewritings does not allow a direct translation into SQL queries, but requires some additional processing steps, depending on the cyclic structure of the Datalog program and the ABox. We show that the set of all ABox justifications can be computed in reasonable time, and compare the performance with Soufflé, a Datalog engine that also supports explanations.