The Bible affirms the law of sowing and reaping. What you sow, you must also reap. If you sow bad behavior, you will reap bad consequences. If you sow kindness, you will reap the same. All of that works pretty much as predicted. And then there is this verse.
If the law of sowing and reaping holds, sowing in tears means you will reap a flood of tears. You have to sow joy to reap the same. But this verse stubbornly refuses to comply with the law as we understand it. This is a promise from God.
So we also need to quote verse 6. 6 He who goes out weeping, bearing the seed for sowing, shall come home with shouts of joy, bringing his sheaves with him. The law still applies (this in a literal sense). As we go out to sow seed, we are weeping. When we go to reap, we are joyful at the harvest. Tears aren’t being down, but seed. Tears reflect our emotional state as we are in the act of sowing.
I believe that when they went out to sow, this grain seed represented the last of their food, a sense of security. To sow it meant to trust their last meal to God with only hope of a return. This is not unlike sacrificial giving, when you give when it hurts to do so. When giving to God means you will be giving up something else that you treasure. That would be sowing in tears. The promise here is that you will reap with joy when the harvest is finally tallied. This is consistent with the law of sowing and reaping.
God bless you today!