Kehillah in Corinth I 10:6-8 Orthodox Jewish Bible (OJB)
7 Neither should you become ovdei elilim (idolaters), as some of them did, as it has been written, "And the people sat to eat and to drink and they got up to revel” SHEMOT 32:6.
8 Neither should we commit zenut as some of them committed zenut and fell in one day twenty-three thousand [BAMIDBAR 25:1,9]. [T.N. if Rav Sha’ul is not giving the number that died in one day, a very famous and devastating twenty-four hour period, (with BAMIDBAR 25:4 mentioning other executions and the subsequent total being 24,000 [Bamidbar 24:9]), then Rav Sha’ul is referring to those who died in Shemot 32:35, quoting as he does Shemot 32:6 in 1C 10:7]