Deuteronomy 27:5

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 20:20

20:20 However, you may chop down any tree you know is not suitable for food, ¹  and you may use it to build siege works ²  against the city that is making war with you until that city falls.

[20:20]  ¹ tn Heb “however, a tree which you know is not a tree for food you may destroy and cut down.”

[20:20]  ² tn Heb “[an] enclosure.” The term מָצוֹר (matsor) may refer to encircling ditches or to surrounding stagings. See R. de Vaux, Ancient Israel, 238.