Reference for Peah 4:7

הִקְדִּישׁ קָמָה וּפָדָה קָמָה, חַיָּב. עֳמָרִין וּפָדָה עֳמָרִין, חַיָּב. קָמָה וּפָדָה עֳמָרִין, פְּטוּרָה, שֶׁבִּשְׁעַת חוֹבָתָהּ הָיְתָה פְטוּרָה:

One who dedicated standing crop [to the Temple] and redeemed it, he is obligated [to give <i>Peah</i>]. One who dedicated cut sheaves and redeemed them, he is obligated. [One who] dedicated standing crop and redeemed [after it became] cut sheaves, he is exempt, for at the time that it would have become obligated, it was exempt.

Jastrow