Midrasz do Psalmów 64:78

And further said R. Abin the Levite: "He who leaves his friend [after escorting him a distance] must not say 'Go in peace' but Go with peace.' for Jethro said unto Moses (Ex. 4, 18.) Go with peace. He went and succeeded, but David said to Abshalom (II Sam. 15, 9.) Go in peace. He went and hanged himself." Further said R. Abin the Levite: "He who takes leave of the dead body [after burial] must not say 'Go with peace' but 'Go in peace,' for it is said (Gen. 15, 15.) But thou shalt come to thy fathers in peace." R. Levi b. Chiya said: "He who goes out from the synagogue [after prayer] and enters the house of learning and studies the Torah will be permitted to wait on the Divine Presence, for it is said (Ps. 84, 8.) They go from strength to strength; each of them will appear before God in Zion." R. Elazar in the name of R. Chanina said: "Scholars advance peace in the world, as it is said (Is. 54, 13.) And all thy children shall be taught by the Lord and great shall be the peace of thy children. Read not Banaich (Thy Children), but read it Bonaich (thy builders)"; Great peace have they who love thy Torah and there is no stumbling for them (Ps. 119, 115). Peace be within thy rampart, prosperity within thy palaces (Ib. 122, 7). For my brethren and associates' sake I would fain speak peace concerning Thee (Ib.). For the sake of the house of the Lord our God. I would seek thy good. The Lord will give strength unto his people; The Lord will bless his people with peace.