Sahih Muslim Book 45, Hadith 105
" By Allah, let that accompany us not which has been damned, or he said like it."
Go ahead (but that dromedary did not move). She (that slave-girl), out of anger, said: O Allah, let that (dromedary) be damned. Thereupon Allah's Apostle (ﷺ) said: Let the dromedary on which the curse has been invoked not proceed with us.
It does not seem proper for a Siddiq that he should be an invoker of curse.