Assembly (30, 40) for endoscopically securing gastrointestinal tissue folds (78, 88), comprising: a first tissue anchor (11, 41) and a second tissue anchor (32, 42), a first suture thread part (13, 43) and a second suture thread part (14, 43, 44), each of the first and second suture thread parts having a connected end (131, 142) and a free end (132, 141) opposite the connected end, wherein the first suture thread part and the second suture thread part are tied to each other through a sliding knot, such that the first suture thread part forms a post of the sliding knot along which the sliding knot is arranged to slide during tightening of the assembly and such that the second suture thread part (14, 43) wraps around the post to create the sliding knot, wherein the assembly is configured to be tightened by sliding the knot along the post, wherein the first suture thread part extends from the first anchor (11, 41) to past the sliding knot where the first suture thread part's free end forms a post free end, and the second suture thread part extends from the second anchor (32, 42) to past the sliding knot where the second suture thread part's free end is free, such that the sliding knot is interposed between the first and second anchors, characterised in that the first anchor (11, 41) or the second anchor (32, 42) comprises a first through hole (121, 121'), and in that the post free end (132, 44) slidingly passes through the first through hole (121, 121'), the first through hole having a size preventing the sliding knot to pass through the first through hole, such that the respective anchor can be used as a knot retainer during tightening. a first tissue anchor (11, 41) and a second tissue anchor (32, 42), a first suture thread part (13, 43) and a second suture thread part (14, 43, 44), each of the first and second suture thread parts having a connected end (131, 142) and a free end (132, 141) opposite the connected end, wherein the first suture thread part and the second suture thread part are tied to each other through a sliding knot, such that the first suture thread part forms a post of the sliding knot along which the sliding knot is arranged to slide during tightening of the assembly and such that the second suture thread part (14, 43) wraps around the post to create the sliding knot, wherein the assembly is configured to be tightened by sliding the knot along the post, wherein the first suture thread part extends from the first anchor (11, 41) to past the sliding knot where the first suture thread part's free end forms a post free end, and the second suture thread part extends from the second anchor (32, 42) to past the sliding knot where the second suture thread part's free end is free, such that the sliding knot is interposed between the first and second anchors, characterised in that the first anchor (11, 41) or the second anchor (32, 42) comprises a first through hole (121, 121'), and in that the post free end (132, 44) slidingly passes through the first through hole (121, 121'), the first through hole having a size preventing the sliding knot to pass through the first through hole, such that the respective anchor can be used as a knot retainer during tightening.