Some people feel that Gurbani contains seemingly contradictory references on the subject of Jap and Tap i.e. remembrance and penance. However if we see the context in which they are used it becomes clear that there is no contradiction.

Let us first see what these terms mean. In the Hindu practices Jap is taken as Simran or reciting some thing like a Mantra. Guru Nanak gives the Gurmat thus:

ਐਸਾ ਗਿਆਨੁ ਜਪਹੁ ਮਨ ਮੇਰੇ ॥ ਹੋਵਹੁ ਚਾਕਰ ਸਾਚੇ ਕੇਰੇ ॥੧॥ ਰਹਾਉ ॥ ੧ ੭੨੮
Aisā gi▫ān japahu man mere.Hovhu cẖākar sācẖe kere. ||1|| rahā▫o.

Remember this wisdom, my mind: Serve the Eternal. Pause and contemplate.

Serving the Creator means obeying Divine commands or the laws of nature. So Jap in Gurmat is more than mere Simran it involves emulation as well.

Tap or penance means actions to atone for wrong-doings. Guru Sahib says on Tap:

ਜਗਨ ਹੋਮ ਪੁੰਨ ਤਪ ਪੂਜਾ ਦੇਹ ਦੁਖੀ ਨਿਤ ਦੂਖ ਸਹੈ ॥ ਰਾਮ ਨਾਮ ਬਿਨੁ ਮੁਕਤਿ ਨ ਪਾਵਸਿ ਮੁਕਤਿ ਨਾਮਿ ਗੁਰਮੁਖਿ ਲਹੈ ॥੧॥ ੧ ੧੧੨੭
Jagan hom punn ṯap pūjā ḏeh ḏukẖī niṯ ḏūkẖ sahai.Rām nām bin mukaṯ na pāvas mukaṯ nām gurmukẖ lahai. ||1||

In order to atone for past transgressions, one offers sacrificial fires, penances, charity and worship, torturing the body for long periods; but one cannot get Mukti or freedom from vices and their effects without (Raam naam) Divine virtues; Mukti is obtained by the Gurmukh, one who follows the guru, through Naam. 1. (M: 1, p 1127).

The fifth Guru reinforces the idea thus:

ਹੋਮ ਜਗ ਜਪ ਤਪ ਸਭਿ ਸੰਜਮ ਤਟਿ ਤੀਰਥਿ ਨਹੀ ਪਾਇਆ ॥ ਮਿਟਿਆ ਆਪੁ ਪਏ ਸਰਣਾਈ ਗੁਰਮੁਖਿ ਨਾਨਕ ਜਗਤੁ ਤਰਾਇਆ ॥੪॥੧॥੧੪॥ ੫ ੧੧੩੯
Hom jag jap ṯap sabẖ sanjam ṯat ṯirath nahī pā▫i▫ā.Miti▫ā āp pa▫e sarṇā▫ī gurmukẖ Nānak jagaṯ ṯarā▫i▫ā. ||4||1||14|

One does not find God by offering sacrificial fires, Jap, Tap, Sanjam or going to the river banks and bathing at pilgrim centers; God is found by dissolving ego and submitting to the guru’s teachings; this is the way the world/creatures may be saved. 4. 1. 14. (M: 5, p 1139).

Some times when these two are taken together, Sanjam i.e. control of Karam Indre or action organs is also added.

Guru Nanak rejects ritual Jap, Tap, Sanjam saying:

ਜਪ ਤਪ ਸੰਜਮ ਕਰਮ ਨ ਜਾਨਾ ਨਾਮੁ ਜਪੀ ਪ੍ਰਭ ਤੇਰਾ ॥ ਗੁਰੁ ਪਰਮੇਸਰੁ ਨਾਨਕ ਭੇਟਿਓ ਸਾਚੈ ਸਬਦਿ ਨਿਬੇਰਾ ॥੩॥੬॥ ੧ ੮੭੮
Jap ṯap sanjam karam na jānā nām japī parabẖ ṯerā.Gur parmesar Nānak bẖeti▫o sācẖai sabaḏ niberā. ||3||6||

I do not practice recitation of Mantras, penaces, control of action organs or other rituals as atonement for past wrong-doings; I recount and emulate Your virtues, O God. Says Nanak, by finding and following the guru, the Divine manifestation, my account of deeds is settled. 3. 6. (M: 1, 878).

However the third Guru applies the above terms like this:

ਗੁਰਮੁਖਿ ਜਪ ਤਪ ਸੰਜਮੀ ਹਰਿ ਕੈ ਨਾਮਿ ਪਿਆਰੁ ॥ ਗੁਰਮੁਖਿ ਸਦਾ ਧਿਆਈਐ ਏਕੁ ਨਾਮੁ ਕਰਤਾਰੁ ॥ ਨਾਨਕ ਨਾਮੁ ਧਿਆਈਐ ਸਭਨਾ ਜੀਆ ਕਾ ਆਧਾਰੁ ॥੪॥੭॥੪੦॥ ੩ ੨੯

Gurmukẖ jap ṯap sanjmī har kai nām pi▫ār.Gurmukẖ saḏā ḏẖi▫ā▫ī▫ai ek nām karṯār.Nānak nām ḏẖi▫ā▫ī▫ai sabẖnā jī▫ā kā āḏẖār. ||4||7||40||

The Gurmukh practices Jap, Tap, and Sanjam with the love of Akal Purakh’s virtues in mind. The Gurmukh ever focuses on the unique virtues of the Creator; Says Nanak: let us keep in mind Divine virtues, which sustain all living beings. 4. 7. 40. (M: 3, p 29).

We also read in Rehras Sahib daily:

ਜਪੁ ਤਪੁ ਸੰਜਮੁ ਧਰਮੁ ਨ ਕਮਾਇਆ ॥ ਸੇਵਾ ਸਾਧ ਨ ਜਾਨਿਆ ਹਰਿ ਰਾਇਆ ॥ ਕਹੁ ਨਾਨਕ ਹਮ ਨੀਚ ਕਰੰਮਾ ॥ ਸਰਣਿ ਪਰੇ ਕੀ ਰਾਖਹੁ ਸਰਮਾ ॥੨॥੪॥ ੫ ੧੨
Jap ṯap sanjam ḏẖaram na kamā▫i▫ā.Sevā sāḏẖ na jāni▫ā har rā▫i▫ā.Kaho Nānak ham nīcẖ karammā.Saraṇ pare kī rākẖo sarmā. ||2||4||

I have neither acted on the principles of Jap, Tap and Sanjam, nor have followed the teachings of the guru O God; my deeds are unbecoming; I have sought Your sanctuary, my Master; please save my honor. 2. 4. (M: 5, p 12).

As may be seen whereas the Hindu perception of Jap, Tap and Sanjam is ritualistic, in Gurmat it focuses on recounting and emulation of the virtues of the Divine as far as humanly possible.

Some people seem to feel that the following verse of Guru Nanak contradicts Gurmat:

ਜਪ ਤਪ ਕਾ ਬੰਧੁ ਬੇੜੁਲਾ ਜਿਤੁ ਲੰਘਹਿ ਵਹੇਲਾ ॥ ਨਾ ਸਰਵਰੁ ਨਾ ਊਛਲੈ ਐਸਾ ਪੰਥੁ ਸੁਹੇਲਾ ॥੧॥ 1 729
Jap ṯap kā banḏẖ beṛulā jiṯ langẖėh vahelā.Nā sarvar nā ūcẖẖlai aisā panth suhelā. ||1||
This Shabad is in response to the one by Sheikh Farid which starts thus:

ਬੇੜਾ ਬੰਧਿ ਨ ਸਕਿਓ ਬੰਧਨ ਕੀ ਵੇਲਾ॥ ਭਰਿ ਸਰਵਰੁ ਜਬ ਊਛਲੈ ਤਬ ਤਰਣੁ ਦੁਹੇਲਾ ॥੧॥ ਫ ੭੯੪

Literal meaning: I could not build a boat when it could have been done; when the pool/sea becomes turbulent it will be hard to get across. (Farid, p 794).

Message: One neglects to recount and emulate Divine virtues in life in order to overcome vices; but the vices accumulate and they cause turbulence in the mind. It is then hard to overcome them and get across the world ocean.

Note: In the above context Gurbani uses the concept of Bhav Saagar, Bhav Jal or Bhai Jal all meaning ‘the terrifying world ocean’, which is hard to cross.

The above Shabad of Sheikh Farid exhibits despondency; Guru Nanak replies to it almost word by word to indicate high spirits, Chardi Kala, when one follows the path of Gurmat, starting thus:

ਜਪ ਤਪ ਕਾ ਬੰਧੁ ਬੇੜੁਲਾ ਜਿਤੁ ਲੰਘਹਿ ਵਹੇਲਾ ॥ ਨਾ ਸਰਵਰੁ ਨਾ ਊਛਲੈ ਐਸਾ ਪੰਥੁ ਸੁਹੇਲਾ ॥੧॥ 1 729
Jap ṯap kā banḏẖ beṛulā jiṯ langẖėh vahelā.Nā sarvar nā ūcẖẖlai aisā panth suhelā. ||1||
Build a boat of Jap Tap that takes you across quickly; there will then be no ocean of vices and so no turbulence; thus the journey of life will be pleasant. 1. (M: 1, p 729).

The Rahau Tuk of the Shabad clarifies that it is Naam that helps overcome vices:

ਤੇਰਾ ਏਕੋ ਨਾਮੁ ਮੰਜੀਠੜਾ ਰਤਾ ਮੇਰਾ ਚੋਲਾ ਸਦ ਰੰਗ ਢੋਲਾ ॥੧॥ ਰਹਾਉ ॥ ੧ ੭੨੯
Ŧerā eko nām manjīṯẖ▫ṛā raṯā merā cẖolā saḏ rang dẖolā. ||1|| rahā▫o.

O God, Your unique virtues are the dye (a fast colour prepared from the roots of plant named Madder) which gives a fast color to my mind so as to be ever imbued with Divine love. Pause and contemplate.

The Hindu and Gurmat concepts have common words but different essence.