Charles Ellicott Commentary Psalms 126:6

"He that goeth forth and weepeth, bearing seed for sowing, Shall doubtless come again with joy, bringing his sheaves [with him]." — Psalms 126:6 (ASV)

The original is very expressive, by the idiom of an infinitive combined with a finite verb:
“He shall walk, and walk and weep,
Bearing the handful of seed:
He shall come, and come with singing,
Bearing his sheaves.”

Here, we must certainly see an extension and not a mere repetition of the previous figure, for the very form of the expression suggests the long, patient labour of the sower, and the reward which patience and perseverance always bring—a harvest in proportion to the toil and trouble of seed-time. The words of the prophet Haggai (Haggai 1:10–11; Haggai 2:19), contemporary with the Return, should be compared.

The word translated “precious” in the Authorized Version may be correctly represented by “handful.” Its meaning is “drawing”; and from Amos 9:13 (see the marginal note), we see that the sower was called “the drawer of seed,” no doubt because the hand is repeatedly drawn out for the cast from the bag or basket containing the seed. Others translate it as “seed-basket” here. The contrast so beautifully painted in this verse was certainly realised when the priests and Levites, and the rest of the children of the captivity, kept the dedication of the house of God with joy (Ezra 6:16; Nehemiah 12:42).