Jastrow: סִיעַ

סִיעַ , Pi. סִיֵּיעַ (denom. of סִיעָה) [to accompany, join a caravan, escort,] to aid, assist. Sabb. 104ᵃ; Yoma 38ᵇ, a. e. מְסַיְּיעִים אותו, v. טָהֵר. Sifra K’dosh., Par. 1, ch. II לא תְסַיֵּיעַ את העני do not assist one poor man (in gleaning, to the injury of another poor man). Bets. 22ᵃ מְסַיֵּיעַ אין בו ממש assisting (the gentile in an operation on the Holy Day) is no real act; a. fr.—Trnsf. to support an opinion of, to prove in favor of. Snh. 91ᵇ ומקרא מְסַיְּיעוֹ and a Bible verse supports him. Y. ib. IV, beg. 22ᵃ ובא חבירו וסִיְּיעוֹ and a fellow witness came and confirmed his evidence; a. fr.—[Tosef. Kil. III, 12 סייעתו ed. Zuck. Var, read: סיערתו, v. סָעַר II.]