27:5 Then you must build an altar there to the Lord your God, an altar of stones – do not use an iron tool on them.
Deuteronomy 23:25
23:25 When you go into the ripe grain fields of your neighbor you may pluck off the kernels with your hand, 1 but you must not use a sickle on your neighbor’s ripe grain.
1 sn For the continuation of these practices into NT times see Matt 12:1-8; Mark 2:23-28; Luke 6:1-5.