Note: This is an imprecatory psalm (a psalm in which the author calls on God to bring misfortune and disaster upon His enemies) along with Psalms 69-71 and 137.
A song of ascents.
129:1 “They have greatly oppressed me from my youth,” let Israel say [an indication that this may be an antiphonal psalm in which the congregation repeated the words of the leader];
129:2 “they have greatly oppressed me from my youth, but they have not gained the victory over me.
129:3 Plowmen [a metaphor for Israel’s enemies] have plowed my back [a metaphor for the suffering of Israel] and made their furrows [a metaphor for wounds; furrows resemble the marks left by scourging] long.
129:4 But the Lord is righteous; he has cut me free from the cords [the yoke] of the wicked.”
129:5 May all who hate Zion [denotes the place where God abides; those who hate it hate God and all He is and stands for] be turned back in shame.
129:6 May they be like grass on the roof [flat roofs covered with shallow dirt in which grassy weeds sprouted; short-lived grass], [note the three-fold worthlessness of the grass…]  which withers before it can grow [as useless as chaff (cf. Ps. 1:4)];
129:7  a reaper cannot fill his hands with it,  nor one who gathers fill his arms.
129:8 [cf. Ruth 2:4 re: this salutation] May those who pass by not say to them, “The blessing of the Lord be on you; we bless you in the name of the Lord. [no one blesses God for worthless weeds (may the wicked be like that); Israel’s enemies did not enjoy the blessings of the Lord]”