Bava Kama9: 6
נָתַן לוֹ אֶת הַקֶּרֶן, וְלֹא נָתַן לוֹ אֶת הַחֹמֶשׁ; מָחַל לוֹ עַל הַקֶּרֶן, וְלֹא מָחַל לוֹ עַל הַחֹמֶשׁ; מָחַל לוֹ עַל זֶה וְעַל זֶה — חוּץ מִפָּחוֹת מִשָּׁוֶה פְּרוּטָה בַקֶּרֶן — אֵינוֹ צָרִיךְ לֵילֵךְ אַחֲרָיו.  נָתַן לוֹ אֶת הַחֹמֶשׁ, וְלֹא נָתַן לוֹ אֶת הַקֶּרֶן; מָחַל לוֹ עַל הַחֹמֶשׁ, וְלֹא מָחַל לוֹ עַל הַקֶּרֶן; מָחַל לוֹ עַל זֶה וְעַל זֶה חוּץ מִשָּׁוֶה פְּרוּטָה בַקֶּרֶן — צָרִיךְ לֵילֵךְ אַחֲרָיו.
[If] he paid him the principal, but did not pay him the fifth; [if] he forgave him the principal, but did not forgive him the fifth; [or] if he forgave him for both —- save less than the worth of a perutah of the principal —- he need not pursue him.  [If] he paid him the fifth, but did not pay him the principal; [if] he forgave him the fifth, but did not forgive him the principal; [or it] he forgave him for both save the worth of a perutah of the principal —- he must pursue him.
Bava Kama9: 7
נָתַן לוֹ אֶת הַקֶּרֶן וְנִשְׁבַּע לוֹ עַל הַחֹמֶשׁ, הֲרֵי זֶה מְשַׁלֵּם חֹמֶשׁ עַל חֹמֶשׁ עַד שֶׁיִּתְמַעֵט הַקֶּרֶן פָּחוֹת מִשָּׁוֶה פְּרוּטָה. וְכֵן בְּפִקָּדוֹן, שֶׁנֶּאֱמַר: ”...בְּפִקָּדוֹן אוֹ־בִתְשׂוּמֶת יָד אוֹ בְגָזֵל אוֹ עָשַׁק אֶת־עֲמִיתוֹ. אוֹ־מָצָא אֲבֵדָה וְכִחֶשׁ בָּהּ וְנִשְׁבַּע עַל־שָׁקֶר” — הֲרֵי זֶה מְשַׁלֵּם קֶרֶן וְחֹמֶשׁ וְאָשָׁם.  ”הֵיכָן פִּקְדוֹנִי?” אָמַר לוֹ: ”אָבַד.” ”מַשְׁבִּיעֲךָ אֲנִי,” וְאָמַר: ”אָמֵן,” וְהָעֵדִים מְעִידִים אוֹתוֹ שֶׁאֲכָלוֹ — מְשַׁלֵּם קֶרֶן. הוֹדָה מֵעַצְמוֹ, מְשַׁלֵּם קֶרֶן וְחֹמֶשׁ וְאָשָׁם.
[If] he paid him the principal and swore to him concerning the fifth, he pays a fifth upon the fifth until the principal dwindles to less than the worth of a perutah. The same applies to a deposit, as it is said (Leviticus 5:21 ff.): ... concerning a deposit, or a loan, or a robbery, or [if] he oppressed another, or found a lost article, and lied about it and swore falsely —- this one pays the principal, a fifth, and a guilt-offering.  “Where is my deposit?” He said to him: “It is lost.” “I adjure you,” and he said: “Amen,” and witnesses testify against him that he ate it —- he pays the principal. [If] he confessed himself, he pays the principal, a fifth, and a guilt-offering.