שובה ישראל עד ה' אלוקיך

Chazal tell us “Reuven returned to the pit” (where Yosef was). Where was Reuven originally? He was fasting and repenting.  Hashem said  ‘no man had ever sinned before me and opened with teshuvah, but you were the first to open with teshuvah, I guarantee you that your sons son will open with teshuvah first’. Hoshea Hanavi is the descendant of Reuven.

 “שובה ישראך עד ה' אלוקיך”.

The question arises, how can we say that Reuven was the first one to do teshuvah, Adam Harishon and Kayin also sinned and did teshuvah?

There are two kinds of sinners. There is the sinner who sins because he was pulled by a strong lust for something and then after the sin he feels guilty.

The second kind of sinner is one who sins knowingly and intentionally. Such a sinner will not care to repent afterwards.

Reuven sinned intentionally, but he had in mind it would be for the sake of honoring his mother, Kibud Eim (שבת: נה). However immediately after he sinned he realizes that it was a mistake since Kibud Av comes before Kibud Eim. Despite having intentions L’eshem shomayaim it was still a sin and this is what he did teshuvah for. This type of teshuvah was never performed before.  Reuven was the first person to do teshuva for sin that was done L’eshem shomayem,

"ואתה פתחתה בתשובה תחילה".

Therefore you will merit for your descendant to be a promoter of teshuva.

 "עומד ופותח בתשובה תחילה", this is referring to Hoshea Hanavi. Hoshea worked hard to awaken the Jews to repent for the sins they did L’shem shamayim.

דרשות תורת חסד סוף דרוש י"א))