Gitin5: 7
חֵרֵשׁ — רוֹמֵז וְנִרְמָז; וּבֶן בְּתֵירָה אוֹמֵר: קוֹפֵץ וְנִקְפָּץ בְּמִטַּלְטְלִין. הַפָּעוֹטוֹת — מִקָּחָן מִקָּח וּמִמְכָּרָן מִמְכָּר בְּמִטַּלְטְלִין.
A deaf-mute gestures and is gestured to; Ben Beseirah, however, says: He moves his lips and is communicated with by means of lip-movements, in [transactions involving] chattels. Young children's purchases are purchases and their sales are sales in [transactions involving] chattels.